Ventricular Tachyarrhythmias

📋 Key Information Summary

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Ventricular tachyarrhythmias encompass sustained monomorphic VT, polymorphic VT, torsades de pointes (TdP), ventricular fibrillation (VF), and inherited arrhythmia syndromes — all carry significant mortality risk in the Australian population.
Sustained monomorphic VT most commonly arises from structural heart disease (ischaemic cardiomyopathy, dilated cardiomyopathy, valvular disease); echocardiography and cardiac MRI are essential baseline investigations.
Catheter ablation is first-line for recurrent idiopathic VT and an important adjunct for VT in structural heart disease; refer to an electrophysiology centre (available in all Australian capital cities and select regional centres).
Antiarrhythmic drugs — amiodarone, sotalol, and flecainide are PBS-listed; mexiletine is available under Special Access Scheme. Beta-blockers are first-line for nearly all ventricular arrhythmia substrates.
Polymorphic VT in the setting of normal QT is managed as per VT with structural heart disease; torsades de pointes requires immediate IV magnesium sulphate and correction of QT-prolonging factors.
All QT-prolonging medications must be reviewed and ceased — use the CredibleMeds database and Australian Adverse Drug Reaction Advisory Committee (ADRAC) lists.
Ventricular fibrillation is the most common initial rhythm in out-of-hospital cardiac arrest (OHCA); early defibrillation and bystander CPR are the most impactful interventions per ANZCOR guidelines.
Targeted temperature management (TTM) at 32–36°C for ≥24 hours is recommended for all comatose post-cardiac-arrest patients per ANZCOR and ILCOR consensus.
ICD implantation is indicated for secondary prevention after cardiac arrest or sustained VT (with reduced LVEF) and for primary prevention when LVEF ≤35% despite ≥3 months of optimal medical therapy (NHFA/CSANZ guidelines).
ICD programming should use high-rate detection zones (≥188–200 bpm) and prolonged detection intervals to reduce inappropriate shocks; all Australian patients should be enrolled in remote monitoring (e.g., Medtronic CareLink, Abbott Merlin).
Electrical storm (≥3 VT/VF episodes in 24 hours) requires emergent management with IV amiodarone, beta-blockade, sedation, and urgent electrophysiology referral for consideration of catheter ablation.
Inherited arrhythmia syndromes — Brugada syndrome, catecholaminergic polymorphic VT (CPVT), and arrhythmogenic right ventricular cardiomyopathy (ARVC) require specialised genetic counselling, family screening, and risk-stratified management at dedicated inherited arrhythmia clinics.
Aboriginal and Torres Strait Islander peoples have higher rates of rheumatic heart disease, cardiomyopathy, and sudden cardiac death, with significant barriers to electrophysiology services in remote and regional areas.

Introduction & Australian Epidemiology

Ventricular tachyarrhythmias are a heterogeneous group of rapid heart rhythms originating below the bundle of His, ranging from relatively benign idiopathic ventricular tachycardia (VT) to immediately life-threatening ventricular fibrillation (VF). They are a leading cause of sudden cardiac death (SCD), which accounts for approximately 20,000–30,000 deaths annually in Australia.

The epidemiology of ventricular tachyarrhythmias in Australia reflects the broader cardiovascular disease burden. Ischaemic heart disease remains the leading predisposing condition, with an estimated 60–70% of VT/VF events occurring in patients with prior myocardial infarction or ischaemic cardiomyopathy. The Australian Institute of Health and Welfare (AIHW) reports that cardiovascular disease accounts for approximately 25% of all deaths, with arrhythmias contributing significantly to out-of-hospital cardiac arrest (OHCA) mortality.

Out-of-hospital cardiac arrest affects approximately 30,000 Australians annually, with an overall survival-to-discharge rate of approximately 10–12%. The Aus-ROC (Australasian Registry of Cardiac Arrest) consortium has demonstrated that VF/pulseless VT as initial rhythm occurs in approximately 20–25% of OHCA cases, and these patients have significantly better outcomes when bystander CPR and early defibrillation are provided.

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Aboriginal and Torres Strait Islander peoples experience sudden cardiac death at 2–3 times the rate of non-Indigenous Australians, with higher prevalence of rheumatic heart disease, remote geography, and delayed access to emergency cardiac services contributing to disparities.

Implantable cardioverter-defibrillator (ICD) therapy has transformed outcomes for patients at high risk of SCD. In Australia, approximately 5,000–6,000 ICDs are implanted annually, with increasing utilisation of cardiac resynchronisation therapy defibrillators (CRT-D). However, significant geographic variation in implantation rates exists, with lower rates in regional and remote areas.

Inherited arrhythmia syndromes, while less common, are increasingly recognised as important causes of SCD in young Australians. National genetic testing programmes and specialised inherited arrhythmia clinics in major cities (Royal Prince Alfred Hospital Sydney, Royal Melbourne Hospital, The Prince Charles Hospital Brisbane, Royal Adelaide Hospital) provide diagnostic and family screening services.

Sustained Monomorphic VT

Sustained monomorphic ventricular tachycardia (SMVT) is defined as VT lasting ≥30 seconds or requiring termination due to haemodynamic compromise. The QRS complex is uniform from beat to beat, reflecting a single re-entrant circuit or focal source. SMVT is the most common sustained ventricular tachyarrhythmia encountered in clinical practice and carries a significant risk of sudden cardiac death.

Structural Heart Disease Assessment

The evaluation of SMVT must systematically identify underlying structural heart disease, as the aetiology fundamentally determines prognosis and management strategy.

Assessment Domain	Investigation	Key Findings	Australian Availability
Left ventricular function	Transthoracic echocardiography (TTE)	LVEF assessment, wall motion abnormalities, valvular disease	Available nationwide; MBS item 55120
Myocardial scar/fibrosis	Cardiac MRI (CMR) with late gadolinium enhancement	Scar localisation, extent, and VT substrate characterisation	Major centres; MBS item 63400 series
Coronary disease	Coronary angiography or CT coronary angiogram	Exclude ischaemic aetiology, guide revascularisation	Angiography: all capital cities; CTA: MBS item 57360
VT mechanism	Electrophysiology (EP) study	Inducibility, circuit mapping, ablation target identification	EP-capable centres in all capitals and select regional hospitals
Infiltrative/inflammatory	CMR, endomyocardial biopsy, genetic testing	Sarcoidosis, ARVC, amyloid, myocarditis	Referral to specialist centres

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Haemodynamically unstable VT: If the patient is pulseless or has severe haemodynamic compromise (systolic BP <90 mmHg, altered consciousness, acute pulmonary oedema), proceed immediately to synchronised cardioversion. Do not delay for pharmacological therapy.

Catheter Ablation

Catheter ablation has become a cornerstone of VT management, with evolving indications from last-resort to early-intervention therapy.

First-Line Ablation

Idiopathic Outflow Tract VT

Focal VT from RVOT or LVOT. Success rate >90%. Radiofrequency or cryoablation. Minimal structural heart disease.

Setting: Electrophysiology lab

Early Ablation

Recurrent VT in Structural Heart Disease

After ≥1 ICD shock or recurrent VT on antiarrhythmic drugs. Substrate-based and/or activation mapping. Success rates 60–80%.

Setting: Specialist EP centre

Emergent Ablation

Electrical Storm Refractory to Medical Therapy

VT storm unresponsive to amiodarone, beta-blockers, and sedation. Performed under mechanical circulatory support if needed. Urgent referral.

Setting: Tertiary cardiac centre with ICU/ECMO backup

Key procedural considerations in the Australian context:

Access: Electrophysiology and catheter ablation services are available in all Australian capital cities. Regional patients may require interstate transfer. Royal Flying Doctor Service (RFDS) facilitates transfers from remote areas.
Techniques: Contemporary VT ablation utilises high-density mapping catheters (e.g., Advisor HD Grid, PentaRay), impedance-based electroanatomical mapping (CARTO 3, EnSite Precision), and integration with pre-procedural CMR/CT imaging.
Complications: Major complication rate approximately 3–7% including cardiac perforation/tamponade (1–2%), vascular access complications, stroke (<1%), and death (<1%).
Medicare rebates: MBS items for EP study (38220–38226) and ablation procedures; out-of-pocket costs may apply in private settings.

Antiarrhythmic Drug Therapy for Monomorphic VT

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Amiodarone

Cordarone X® · Aratac® · Generic · Class III (multi-class)

IV loading (acute VT) 300 mg IV over 20–30 min, then 900 mg over 24 h (or 150 mg IV bolus q10min PRN up to 3 boluses, then 1 mg/min × 6 h, then 0.5 mg/min × 18 h)

Oral (maintenance) 200 mg PO TDS for 1 week → 200 mg PO BD for 1 week → 200 mg PO daily (maintenance)

Paediatric dose 5 mg/kg IV over 20–60 min (max 300 mg), then 10–15 mg/kg/day IV; PO: 10–15 mg/kg/day divided TDS

Renal adjustment None required — hepatically metabolised

Key monitoring TFTs (TSH every 6 months), LFTs, PFTs, slit-lamp eye exam, ECG (QT/QTc), chest X-ray

PBS status ✔ PBS General Benefit (oral) ✔ PBS General Benefit (IV)

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Sotalol

Sotacor® · Generic · Class III (beta-blocking class III)

Adult dose 80–160 mg PO BD (max 320 mg/day); initiate in hospital with QT monitoring

Paediatric dose 1–3 mg/kg/day PO divided BD (max 5 mg/kg/day)

Renal adjustment eGFR 30–60: reduce dose/extend interval; eGFR <30: avoid or use with extreme caution

Key caution Contraindicated if QTc >500 ms. Pro-arrhythmic risk — initiation in monitored setting. Avoid with other QT-prolonging drugs.

PBS status ✔ PBS General Benefit

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Flecainide

Tambocor® · Generic · Class IC

Adult dose 50–200 mg PO BD (start 50 mg BD, titrate)

Paediatric dose 1–3 mg/kg/day PO divided BD–TDS

Renal adjustment eGFR <35: reduce dose by 50%; monitor plasma levels

Key caution CONTRAINDICATED in structural heart disease (CAST trial — increased mortality with ischaemic cardiomyopathy). Use ONLY in structurally normal hearts.

PBS status ✔ PBS General Benefit

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Mexiletine

Mexitil® · Class IB (oral lidocaine analogue)

Adult dose 200 mg PO TDS (max 400 mg TDS); can start 400 mg stat then 200 mg TDS

Renal adjustment eGFR <30: reduce dose and extend interval

Key use Adjunctive therapy with amiodarone for refractory VT; monotherapy for channelopathies

PBS status ✘ Not PBS-listed — Special Access Scheme (SAS) or TGA Authorised Prescriber

Polymorphic VT & Torsades de Pointes

Polymorphic ventricular tachycardia (PVT) is defined as VT with continuously varying QRS morphology, typically rotating around the baseline. Torsades de pointes (TdP) is a specific form of PVT occurring in the setting of QT prolongation (QTc >500 ms), characterised by the twisting of QRS complexes around the isoelectric line. The distinction between PVT with normal QT and TdP is critical, as management differs substantially.

QT Interval Assessment

Systematic QT interval assessment is essential in all patients presenting with polymorphic VT.

QTc (Bazett)	Interpretation	Clinical Action
<440 ms (males) / <460 ms (females)	Normal	PVT managed as per structural heart disease pathway
440–499 ms (males) / 460–499 ms (females)	Borderline prolongation	Review medications, electrolytes; serial ECGs; consider genetic testing
≥500 ms	Significant prolongation	HIGH RISK of TdP — cease all QT-prolonging drugs, correct electrolytes, IV magnesium, continuous telemetry
≥500 ms + syncope or TdP	Critical	Emergent management — MgSO₄, isoprenaline/temporary pacing if recurrent, genetic referral

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Common QT-prolonging medications in Australia: Check ALL current medications against the CredibleMeds.org database. Common offenders include: sotalol, amiodarone, antipsychotics (haloperidol, droperidol, quetiapine), antidepressants (citalopram, escitalopram), macrolide antibiotics (erythromycin, clarithromycin), azole antifungals, ondansetron, metoclopramide, and antimalarials. Cease all offending agents immediately.

Drug-Induced Torsades de Pointes

Drug-induced TdP is the most common acquired cause and is preventable. Risk factors include female sex (2–3× risk), hypokalaemia, hypomagnesaemia, bradycardia, recent cardioversion, high drug concentrations, and congenital subclinical long QT.

1

Cease all QT-prolonging drugs

Immediate cessation of every suspected agent. Document in medication chart and discharge summary.

2

Correct electrolytes

Target K⁺ >4.5 mmol/L and Mg²⁺ >1.0 mmol/L. Replace aggressively with IV supplementation.

3

IV Magnesium Sulphate

First-line therapy — 2 g (8 mmol) IV over 5–10 min, may repeat once in 5–15 min. Infusion 1–2 g/h if recurrent.

4

Increase heart rate

Isoprenaline 2–10 mcg/min IV or temporary transvenous pacing at 90–110 bpm to shorten QT interval.

5

Defibrillation if degenerating

If TdP degenerates to VF, immediate unsynchronised defibrillation per ALS protocols.

Congenital Long QT Syndrome

Congenital long QT syndrome (LQTS) affects approximately 1 in 2,000 Australians and is caused by mutations in cardiac ion channel genes. Key subtypes:

Subtype	Gene	Trigger	First-Line Therapy
LQT1 (30–35%)	KCNQ1	Exercise (swimming), emotional stress	Beta-blockers (nadolol preferred); avoid competitive sport
LQT2 (25–30%)	KCNH2 (hERG)	Auditory stimuli (alarm clocks), emotional stress, QT-prolonging drugs	Beta-blockers; avoid QT drugs; supplement K⁺
LQT3 (5–10%)	SCN5A	Rest/sleep, bradycardia	Beta-blockers + mexiletine; consider LCSD or ICD

Left cardiac sympathetic denervation (LCSD) — thoracoscopic sympathectomy (T2–T4 ganglionectomy) — is available at selected Australian centres and is indicated for LQTS patients with recurrent syncope on maximal beta-blockade who refuse or are unsuitable for ICD implantation.

Magnesium Sulphate Therapy

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Magnesium Sulphate (MgSO₄)

Generic IV formulation · Electrolyte / membrane stabiliser

TdP — first dose 2 g (8 mmol) IV over 5–10 min; may repeat once in 5–15 min if TdP persists

Maintenance 1–2 g (4–8 mmol) IV per hour for 6–24 hours or until QT normalises

Paediatric dose 25–50 mg/kg IV over 5–20 min (max 2 g), then 1–2 mg/kg/h infusion

Renal adjustment Reduce dose 50% in eGFR <30; monitor serum Mg²⁺ levels; risk of toxicity (loss of reflexes, respiratory depression)

Note Magnesium is effective for TdP even when serum Mg²⁺ is normal — the mechanism is membrane stabilisation, not replacement.

PBS status ✔ PBS General Benefit (IV injection)

Polymorphic VT with normal QT interval is most commonly associated with acute myocardial ischaemia and is managed with anti-ischaemic therapy (including emergency coronary angiography), beta-blockers, and amiodarone if ongoing. Lidocaine (lignocaine) 1–1.5 mg/kg IV is an alternative agent in ischaemia-related VT.

Ventricular Fibrillation

Ventricular fibrillation (VF) is a chaotic, disorganised ventricular rhythm that results in immediate loss of cardiac output and, without intervention, death within minutes. VF is the initial rhythm in approximately 20–25% of out-of-hospital cardiac arrests in Australia and is the most treatable cardiac arrest rhythm — survival rates of 30–50% are achievable with early defibrillation.

Cardiac Arrest Management (ANZCOR / ILCOR)

1

Early recognition & call 000

Check responsiveness, call for help, activate Emergency Medical Services (000 in Australia). Send for AED (automated external defibrillator) if available.

2

High-quality CPR

Chest compressions at 100–120/min, depth 5–6 cm (adults), full recoil, minimise interruptions. Compression-to-ventilation ratio 30:2 (or continuous compressions with advanced airway).

3

Early defibrillation

Biphasic shock 150–200 J (or manufacturer-recommended dose). Resume CPR immediately for 2 minutes after each shock. Public-access AEDs are increasingly available in Australian public spaces, sporting venues, and airports.

4

Advanced Life Support (ALS)

IV/IO access, adrenaline 1 mg IV every 3–5 minutes (after 2nd shock for shockable rhythms per ANZCOR 2020), amiodarone 300 mg IV (after 3rd shock), second dose 150 mg IV if needed.

5

Identify & treat reversible causes

4Hs & 4Ts: Hypoxia, Hypovolaemia, Hypo/Hyperkalaemia, Hypothermia; Tension pneumothorax, Tamponade (cardiac), Toxins, Thrombosis (coronary/pulmonary).

6

Post-ROSC care

12-lead ECG, coronary angiography if STEMI or suspected ACS, targeted temperature management, ICU admission. Activate state cardiac arrest receiving centre pathway where available.

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Critical time points: For VF/pulseless VT, every minute of defibrillation delay reduces survival by approximately 7–10%. Bystander CPR doubles to triples survival. Australia's national bystander CPR rate is approximately 50–60% — community AED programmes and first-aid training (St John Ambulance Australia, Australian Red Cross) are essential to improve this.

ICD Therapy for VF Survivors

All survivors of VF cardiac arrest without a clearly reversible cause (e.g., acute ST-elevation myocardial infarction with successful primary PCI and recovery of LVEF >50%) should undergo evaluation for ICD implantation as secondary prevention. Per NHFA/CSANZ guidelines, ICD is indicated when:

VF arrest survivor with LVEF ≤50% after revascularisation and optimal medical therapy (≥4–6 weeks reassessment)
Sustained VT causing haemodynamic compromise with LVEF ≤50%
Unexplained syncope with inducible VT at EP study in the setting of structural heart disease

Targeted Temperature Management (TTM)

Targeted temperature management is recommended for all comatose patients following cardiac arrest with an initial shockable rhythm (VF/pulseless VT).

Parameter	Recommendation
Target temperature	32–36°C (constant target; ANZCOR/ILCOR 2020 — avoid active fever >37.7°C)
Duration	≥24 hours of controlled temperature
Initiation	As soon as possible after ROSC (pre-hospital cooling with cold IV fluids no longer routinely recommended)
Methods	Surface cooling (Arctic Sun, blankets) or endovascular cooling catheter. Routine pre-hospital rapid infusion of cold fluids not recommended (TAME trial — no benefit with TTM at 33°C).
Monitoring	Continuous core temperature (oesophageal, bladder, or intravascular); avoid overshoot <31°C
Rewarming	Controlled at 0.25–0.5°C/hour; maintain normothermia (<37.7°C) for 72 h post-arrest
Australian availability	All tertiary ICUs; retrieval services (adult and paediatric) provide TTM during interhospital transfer

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TAME Trial (2023): The Targeted Hypothermia versus Targeted Normothermia after Out-of-Hospital Cardiac Arrest (TAME) trial demonstrated no benefit of TTM at 33°C compared to strict normothermia (target ≤37.7°C) in comatose OHCA patients. Current ANZCOR guidance recommends avoiding fever (>37.7°C) with a target of 32–36°C, acknowledging that a specific target within this range should be determined by local protocol.

ICD Therapy

Implantable cardioverter-defibrillators (ICDs) are the cornerstone of sudden cardiac death prevention in high-risk patients. In Australia, approximately 5,000–6,000 new ICDs and 1,500–2,000 replacement generators are implanted annually. Both transvenous (TV-ICD) and entirely subcutaneous (S-ICD) systems are available.

ICD Indications (NHFA/CSANZ)

Indication	Criteria	Evidence Level
Primary prevention — ischaemic CMP	LVEF ≤35%, NYHA II–III, ≥40 days post-MI, ≥3 months optimal medical therapy (including GDMT and CRT where appropriate)	Class I (MADIT-II, SCD-HeFT)
Primary prevention — non-ischaemic CMP	LVEF ≤35%, NYHA II–III, ≥3 months optimal medical therapy including GDMT (ACEi/ARB/ARNi, beta-blocker, MRA, SGLT2i)	Class I (DANISH — NHFA concordant with Class I for specific patients)
Secondary prevention	Survived cardiac arrest (VF/pVT) without reversible cause; sustained VT with haemodynamic compromise and LVEF ≤50%	Class I (AVID, CIDS, CASH)
Inherited arrhythmia syndromes	High-risk Brugada, CPVT, ARVC, LQTS with cardiac arrest or recurrent syncope on beta-blockers	Class I–IIa depending on risk score

ICD Programming

Contemporary ICD programming should minimise inappropriate therapies and reduce painful shocks. Evidence from MADIT-RIT, ADVANCE III, and PROVIDE trials supports the following principles:

Single-zone programming (primary prevention): Monitor zone with ATP (anti-tachycardia pacing) before shock at ≥200 bpm (cycle length ≤300 ms). No therapy zone for rates <200 bpm.
Dual-zone programming: VT zone 170–200 bpm (ATP × 8 bursts → shock); VF zone >200 bpm (ATP during charging → shock at 36 J if ATP fails).
Detection duration: Prolong detection to 30/40 intervals (or ≥6–12 seconds) to allow self-termination before therapy delivery.
ATP before shocks: Burst ATP (8 pulses at 88% of VT cycle length) is effective for VT up to 200 bpm and should be delivered even in the VF zone during capacitor charging.
S-ICD programming: Subcutaneous ICD cannot deliver ATP; uses a conditional zone (typically 200–250 bpm with morphology discrimination) to reduce inappropriate shocks.

Appropriate vs Inappropriate Shocks

Type	Aetiology	Management
Appropriate shock	True VT/VF detected and treated correctly	Optimise antiarrhythmic therapy, consider catheter ablation, reassess programming
Inappropriate shock — SVT	Atrial fibrillation, atrial flutter, AVNRT, sinus tachycardia	Rate control, SVT ablation, reprogram discriminators (sudden onset, stability, morphology)
Inappropriate shock — T-wave oversensing	Tall T-waves detected as R-waves (double-counting)	Reprogram sensitivity; adjust sensing vector (S-ICD); correct hyperkalaemia
Inappropriate shock — lead fracture/noise	Lead insulation breach, connector problem	Lead revision or replacement; impedance monitoring on remote follow-up

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Patient psychological impact: ICD shocks (both appropriate and inappropriate) are associated with anxiety, depression, post-traumatic stress disorder, and reduced quality of life. Refer patients to cardiac psychology/psychiatry services and ICD support groups (e.g., SADS Australia, Heart Foundation support programmes). Psychological screening should be routine at follow-up.

Electrical Storm Management

Electrical storm (arrhythmic storm) is defined as ≥3 episodes of VT/VF within 24 hours, each requiring intervention. It carries a mortality rate of 15–25% in-hospital and requires emergent, multidisciplinary management.

1

Haemodynamic support

ICU/CCU admission. Consider mechanical circulatory support (Impella, ECMO) if refractory hypotension. Correct reversible causes (ischaemia, electrolytes, drugs).

2

IV Amiodarone

300 mg IV over 20–30 min, then 900 mg IV over 24 hours. Can give additional 150 mg boluses for recurrent VT.

3

Beta-blockade

IV metoprolol 5 mg q5min (up to 20 mg) or IV propranolol. Esmolol 500 mcg/kg bolus then 50–200 mcg/kg/min if haemodynamic concerns (ultra-short acting).

4

Deep sedation & intubation

General anaesthesia with propofol or ketamine. Reduces sympathetic drive and catecholamine surge. Consider lignocaine 1–1.5 mg/kg IV bolus then 1–4 mg/min infusion.

5

Urgent catheter ablation

For refractory electrical storm, urgent EP study and VT ablation under mechanical circulatory support. Refer to tertiary EP centre. Stellate ganglion block is an adjunctive option.

Remote Monitoring

Remote monitoring of ICDs and CRT-D devices is the standard of care in Australia, enabling early detection of device alerts, arrhythmias, and heart failure decompensation.

Platforms available in Australia: Medtronic CareLink™, Abbott Merlin.net™, Boston Scientific Latitude™, Biotronik Home Monitoring™.
Frequency: Daily automatic transmissions for alerts; routine follow-up every 3–6 months remote, with in-clinic review every 6–12 months.
Benefits: Reduced time to clinical action for atrial fibrillation detection, lead alerts, battery depletion, and heart failure parameters. IN-TIME trial showed mortality benefit with remote monitoring.
Regional and remote access: Remote monitoring is particularly valuable for patients in regional and remote Australia. Mobile phone coverage and satellite connectivity in remote NT, WA, and QLD may require alternative transmission methods — contact device manufacturer for solutions.
Medicare: MBS items for remote monitoring (MBS items 55124, 55125 for device interrogation); some private health funds cover additional telehealth consultations.

Inherited Arrhythmia Syndromes

Inherited arrhythmia syndromes (also known as channelopathies or primary electrical diseases) are genetic conditions that predispose to ventricular tachyarrhythmias and sudden cardiac death, typically in the setting of a structurally normal or minimally abnormal heart. They are increasingly recognised as important causes of SCD in young Australians, often presenting as sudden infant death syndrome (SIDS), unexplained drowning, sudden unexpected death in epilepsy (SUDEP), or death during exercise.

Brugada Syndrome

Brugada syndrome is characterised by distinctive ST-segment elevation in the right precordial leads (V1–V3) with risk of VF and SCD, predominantly in males aged 20–50 years. It is caused primarily by loss-of-function mutations in SCN5A (sodium channel), though the genetic basis is identifiable in only 20–30% of cases.

Feature	Detail
ECG pattern	Type 1 (coved) ST elevation ≥2 mm in V1–V3 followed by negative T-wave — spontaneous or provoked by sodium channel blocker (ajmaline/flecainide test)
Prevalence	Estimated 1:2,000–1:5,000; higher in Southeast Asian populations; variable in Australian population
Risk factors for events	Spontaneous Type 1 pattern, history of syncope, male sex, SCN5A-positive mutation, fever
Provocation test	Ajmaline (1 mg/kg IV over 10 min) — available at major Australian EP centres via TGA Special Access Scheme. Flecainide 2 mg/kg IV (max 150 mg) is an alternative.
Management	ICD for cardiac arrest survivors and high-risk patients (syncope with spontaneous Type 1). Avoid fever (aggressive antipyretics). Avoid alcohol excess, large meals, QT-prolonging drugs. Isoproterenol for electrical storm. Quinidine (oral) for recurrent VF/ICD storms.
Australian clinics	Inherited arrhythmia clinics at Royal Prince Alfred (Sydney), Royal Melbourne, Prince Charles Hospital (Brisbane), Royal Adelaide, Royal Perth

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Fever management: Fever is a potent trigger for VF in Brugada syndrome. All patients and families must be counselled to treat fever aggressively with paracetamol and/or ibuprofen, and to present to hospital if fever >38°C does not respond to antipyretics. Avoid all sodium channel-blocking drugs (procainamide, flecainide, propafenone, tricyclic antidepressants, local anaesthetics — caution with dental and surgical procedures).

Catecholaminergic Polymorphic VT (CPVT)

CPVT is a highly malignant inherited arrhythmia syndrome characterised by exercise- or emotion-triggered bidirectional or polymorphic VT, typically presenting in childhood or adolescence with a structurally normal heart and normal resting ECG. It is caused by mutations in RYR2 (ryanodine receptor — autosomal dominant, ~60% of cases) or CASQ2 (calsequestrin — autosomal recessive).

1

Diagnosis

Exercise stress test (treadmill or bicycle) is the key diagnostic provocation — bidirectional VT or polymorphic VT developing at heart rates >120 bpm is characteristic. Genetic testing for RYR2 and CASQ2 mutations.

2

Beta-blockers

First-line: nadolol 1–2 mg/kg/day (long-acting, non-selective) or propranolol. AVOID atenolol and metoprolol (inferior efficacy in CPVT). Maximum tolerated dose.

3

Flecainide

Add-on therapy to beta-blockers for breakthrough VT on exercise testing. 2–3 mg/kg/day divided BD. Reduces exercise-induced arrhythmias by 70–80% (based on CPVT registry data). PBS-listed but used off-label for CPVT.

4

ICD implantation

For cardiac arrest survivors, recurrent syncope on maximal medical therapy, or sustained VT on exercise testing despite beta-blockers + flecainide. Caution: ICD shocks can trigger catecholamine surges and VF storms in CPVT — ensure beta-blockers optimised pre-implant.

5

Lifestyle modification

Strict avoidance of competitive sport and high-intensity exercise. Avoid emotional stress triggers. Swimming prohibited (drowning risk). Exercise testing to guide safe activity levels.

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)

ARVC (also termed arrhythmogenic cardiomyopathy, ACM) is a genetic cardiomyopathy characterised by fibro-fatty replacement of the myocardium — predominantly the right ventricle but increasingly recognised with biventricular or left-dominant forms. It is an important cause of SCD in young athletes and is caused by mutations in desmosomal genes (PKP2, DSP, DSG2, DSC2, JUP).

Diagnostic Category	Criteria (2010 Task Force / 2020 Padua Criteria)
Definite diagnosis	2 major, OR 1 major + 2 minor, OR 4 minor from different categories
Borderline	1 major + 1 minor, OR 3 minor
Possible	1 major OR 2 minor

Diagnostic domains include: (1) Global/regional dysfunction and structural alterations (echo, CMR); (2) Tissue characterisation (endomyocardial biopsy — fibrofatty replacement); (3) Depolarisation/conduction abnormalities (epsilon waves, terminal QRS duration ≥55 ms in V1–V3); (4) Repolarisation abnormalities (T-wave inversion V1–V3 in adults >14 years); (5) Arrhythmias (non-sustained VT with LBBB morphology, >500 PVCs/24 h); (6) Family history (confirmed ARVC or SCD with ARVC at autopsy).

Management of ARVC:

Exercise restriction: Avoid competitive sport and high-intensity endurance exercise. Exercise accelerates disease progression and arrhythmia risk.
Pharmacotherapy: Beta-blockers (sotalol or nadolol), antiarrhythmic drugs (sotalol preferred, amiodarone for refractory cases).
Catheter ablation: For recurrent VT despite medical therapy. Epicardial approach frequently required (available at major Australian EP centres). Substrate-based ablation. Recurrence rates are higher than in ischaemic VT.
ICD: For cardiac arrest survivors, sustained VT, haemodynamically tolerated VT, and progressive RV/LV dysfunction. Primary prevention ICD in high-risk patients (significant ventricular dysfunction, syncope, non-sustained VT).
Heart transplantation: For refractory heart failure or arrhythmias unresponsive to all therapies. Refer to transplant centres (St Vincent's Sydney, Alfred Melbourne, Prince Charles Brisbane).

Investigations

Essential 12-Lead ECG Baseline assessment — QTc measurement, bundle branch block morphology, epsilon waves, Brugada pattern, ischaemic changes, pre-excitation. During VT: QRS axis, morphology (LBBB vs RBBB), concordance to localise origin.

Essential Continuous telemetry / Holter monitoring (24–72 h) Document burden of ventricular ectopy, non-sustained VT, AF. For inherited syndromes — exercise stress test (CPVT), 7-day Holter. MBS item 11012.

Essential Transthoracic echocardiography LVEF, wall motion, valvular disease, RV structure/function (ARVC assessment: RVOT PLAX ≥32 mm, RVOT PSAX ≥36 mm, fractional area change ≤33%). MBS item 55120.

Available Cardiac MRI (CMR) with LGE Myocardial scar/fibrosis characterisation, tissue characterisation (oedema, fat), ARVC assessment (RV wall motion, fat/fibrosis). MBS item 63400. Available in all capital cities.

Available Coronary angiography / CT coronary angiogram Exclude ischaemic aetiology. Angiography via femoral or radial approach. CTCA (MBS item 57360) for low-intermediate risk patients. Invasive angiography available in all capitals and select regional centres.

Available Electrophysiology (EP) study Programmed ventricular stimulation for VT induction. Risk stratification post-MI. Catheter ablation mapping and therapy. MBS items 38220–38226. Available in all capital cities.

Specialist Genetic testing Comprehensive arrhythmia gene panels (LQTS, Brugada, CPVT, ARVC, DCM genes). Available through commercial labs (Sonic Genetics, PathWest, Victorian Clinical Genetics Services). Medicare rebate for targeted mutation testing in index case. Cascade screening for family members.

Specialist Pharmacological provocation testing Ajmaline/flecainide test for Brugada syndrome. Epinephrine challenge for LQTS. Performed in EP lab with continuous monitoring. Ajmaline via SAS.

Available Exercise stress test Key diagnostic test for CPVT (bidirectional VT at peak exercise). Exercise-induced VT localisation. MBS item 11015.

Available Blood tests Electrolytes (K⁺, Mg²⁺, Ca²⁺, PO₄³⁻), troponin (rule out acute MI), TFTs (amiodarone), FBC, LFTs, renal function, toxicology screen (drug-induced arrhythmia). BNP/NT-proBNP for heart failure assessment.

Specialist Endomyocardial biopsy Suspected cardiac sarcoidosis, myocarditis, or ARVC with diagnostic uncertainty. Performed at tertiary centres. Sensitivity limited by sampling error.

Risk Stratification & Severity Scoring

Risk stratification for ventricular arrhythmias and SCD is essential for guiding ICD implantation decisions, activity restrictions, and follow-up intensity. The approach varies by underlying substrate.

Ischaemic Cardiomyopathy — SCD Risk Stratification

Low Risk

LVEF >40%, no inducible VT

LVEF >40% post-MI with optimal revascularisation. No inducible VT at EP study. NYHA I. Low arrhythmic risk — no ICD indicated.

Setting: Cardiology outpatient follow-up

Moderate Risk

LVEF 36–40%, or LVEF ≤35% early post-MI

LVEF 36–40% with non-sustained VT or inducible VT at EP study warrants ICD consideration. LVEF ≤35% early post-MI — defer ICD assessment ≥40 days (early revascularisation effect).

Setting: Heart failure clinic with EP assessment

High Risk

LVEF ≤35%, NYHA II–III, on GDMT ≥3 months

Meets primary prevention ICD criteria (MADIT-II/SCD-HeFT). LVEF reassessment after ≥3 months of GDMT (including ARNi, beta-blocker, MRA, SGLT2i). If LVEF remains ≤35%, proceed with ICD.

Setting: EP/Heart Failure multidisciplinary team

Inherited Arrhythmia — Risk Stratification Tools

Condition	Risk Score / Tool	High-Risk Features
LQTS	Schwartz score (clinical); LQT1/2/3 genotype	QTc >500 ms, syncope on therapy, LQT3, infancy events, male LQT2
Brugada	Shanghai score (2016)	Spontaneous Type 1 ECG, history of syncope, VF, male sex, SCN5A +
CPVT	Clinical (genotype, exercise test response)	Prior cardiac arrest, syncope on beta-blockers, supraventricular arrhythmias, young age at diagnosis
ARVC	Risk factors (no validated score)	Prior sustained VT/VF, significant RV dilation, LV involvement, male sex, compound desmosomal mutations, competitive sport history

Monitoring

Ongoing monitoring is essential for patients with ventricular tachyarrhythmias, encompassing arrhythmia surveillance, medication safety, device function, and psychosocial wellbeing.

Monitoring Domain	Frequency	Tests / Assessments
ECG monitoring	Every visit (3–6 monthly); continuous after drug initiation	12-lead ECG (QTc, QRS duration, HR, arrhythmia recurrence); Holter/loop recorder for symptom correlation
Amiodarone toxicity	TFTs every 6 months; LFTs, PFTs annually; ophthalmology annually; chest X-ray at baseline and annually	TSH, fT4, fT3; ALT, AST, GGT; DLCO; slit-lamp examination
Sotalol monitoring	After every dose change; then every 6 months	ECG (QTc <500 ms), renal function, electrolytes
ICD device follow-up	Remote: daily transmissions (alerts), routine 3–6 monthly. In-clinic: every 6–12 months	Battery status, lead impedance, sensing thresholds, arrhythmia episodes, shock/ATP appropriateness, heart failure diagnostics
LVEF reassessment	3–6 monthly until stable; then annually	TTE — guide medical therapy optimisation and CRT/ICD decisions
Genetic/family screening	At diagnosis and when new family members identified	Cascade genetic testing; clinical screening (ECG, exercise test, echo) for genotype-positive/phenotype-negative family members
Psychological wellbeing	Every visit — validated screening	PHQ-9 (depression), GAD-7 (anxiety), ICD-specific anxiety scales. Referral to cardiac psychology. SADS Australia support groups.

ℹ️

Driving restrictions (Austroads/NHFA): Private vehicle driving: ICD implantation for primary prevention — no restriction; ICD implantation for secondary prevention — cease driving for ≥2 weeks post-implant; ICD shock (appropriate) — cease driving for ≥6 months. Commercial driving licence: generally disqualified following ICD implantation. Refer to the Austroads Assessing Fitness to Drive guidelines (2022 edition) for current requirements.

Special Populations

🤰 Pregnancy

Ventricular arrhythmias in pregnancy VT in pregnancy is uncommon but may occur in structural heart disease, peripartum cardiomyopathy, or inherited channelopathies (LQTS — risk is highest in the postpartum period, especially LQT2).

Acute VT management Synchronised cardioversion is safe in all trimesters. IV amiodarone crosses the placenta (risk of neonatal thyroid dysfunction, bradycardia) — use only for life-threatening refractory VT. IV lignocaine is preferred first-line antiarrhythmic. IV procainamide is an option.

Beta-blockers Metoprolol and labetalol are preferred in pregnancy (Category C — foetal growth restriction risk, neonatal bradycardia/hypoglycaemia). Nadolol — limited safety data. Atenolol is associated with foetal growth restriction and should be avoided.

LQTS in pregnancy Continue beta-blockers throughout pregnancy and postpartum. LQT2 patients are at particular risk postpartum — avoid sleep deprivation and loud auditory stimuli. Breastfeeding is not contraindicated with beta-blockers.

ICD in pregnancy ICD implantation can be performed during pregnancy if clinically indicated (with foetal shielding). Existing ICDs function normally; pregnancy does not affect device function. Remote monitoring should continue.

👶 Paediatrics

Idiopathic VT in children Outflow tract VT and fascicular VT are the most common forms of sustained VT in children with structurally normal hearts. Most are benign and may resolve spontaneously. Catheter ablation has high success rates (>85%) at paediatric EP centres (Royal Children's Hospital Melbourne, Children's Hospital Westmead Sydney, Queensland Children's Hospital Brisbane).

Inherited arrhythmias in children CPVT typically presents in childhood with exercise-induced syncope. LQTS may present with seizures, syncope, or SIDS. Paediatric genetic testing requires careful pre-test counselling and parental consent.

ICD in children ICD implantation in children is indicated for high-risk inherited arrhythmia syndromes and post-cardiac arrest. Subcutaneous ICD is preferred for smaller children (avoids transvenous lead issues with growth). General anaesthesia required for implantation.

Antiarrhythmic drugs in children Weight-based dosing essential. Amiodarone — monitor thyroid and growth. Beta-blockers (nadolol preferred in CPVT) — monitor for bronchospasm and exercise intolerance. Flecainide — monitor QRS width and plasma levels.

👴 Elderly

ICD decision-making ICD benefit diminishes with advancing age and comorbidities. Shared decision-making is essential. Consider competing mortality risks, frailty (Clinical Frailty Scale), cognitive impairment, and patient goals. NHFA guidelines recommend individualised assessment rather than age-based exclusion.

Amiodarone toxicity Higher risk of thyroid, pulmonary, and hepatic toxicity in elderly. Regular monitoring imperative. Consider lower maintenance doses (100–200 mg daily). Drug interactions common — review all medications (warfarin dose reduction, digoxin dose reduction).

Falls and ICD Elderly patients with ICDs are at higher risk of falls. Lead dislodgement and inappropriate shocks from physical artefact may occur. Falls prevention programmes (e.g., Stepping On — Australian programme) recommended.

🫘 Renal Impairment

Electrolyte management CKD patients are at high risk of hyperkalaemia, hypomagnesaemia, and hypocalcaemia — all pro-arrhythmic. Regular electrolyte monitoring and correction are essential. Hyperkalaemia threshold for intervention lower in CKD (K⁺ >5.5 mmol/L) due to chronic adaptation.

Sotalol Predominantly renally cleared — dose reduction mandatory in eGFR <60 mL/min. Avoid if eGFR <30 mL/min. High risk of TdP in renal impairment.

Dialysis patients VT/VF risk increased peri-dialysis due to electrolyte shifts. ICD implantation is feasible but carries higher infection risk. Avoid subclavian vein access on ipsilateral side to arteriovenous fistula.

🫁 Hepatic Impairment

Amiodarone Hepatically metabolised — avoid in severe hepatic impairment (Child-Pugh C). Lower loading doses in moderate impairment. Monitor LFTs at baseline and every 6 months. Amiodarone-induced hepatitis can occur at any time — transaminases >3× ULN warrants dose reduction or cessation.

Flecainide Reduced clearance in hepatic impairment — reduce dose and monitor plasma levels. Contraindicated in severe liver disease.

Drugs safe in hepatic impairment Sotalol (renal clearance) is the preferred antiarrhythmic with Class III action in hepatic impairment. Beta-blockers (dose adjustment for highly hepatically cleared agents such as propranolol).

🛡️ Immunocompromised

Cardiac transplant recipients Ventricular arrhythmias in transplanted hearts are rare but carry high mortality. Denervation changes drug sensitivity. Graft vasculopathy is the most common substrate. ICD implantation in transplant recipients requires careful anatomical planning.

Drug interactions Amiodarone interacts with tacrolimus, cyclosporine, and sirolimus (increased levels — dose adjustment required). Azole antifungals inhibit amiodarone metabolism. Macrolide antibiotics (QT prolongation risk).

HIV-associated cardiomyopathy Increasing prevalence with ageing HIV population in Australia. Dilated cardiomyopathy and VT risk. Some antiretrovirals (QT-prolonging: atazanavir, efavirenz) should be reviewed.

Aboriginal and Torres Strait Islander Health Considerations

Aboriginal and Torres Strait Islander Health

Aboriginal and Torres Strait Islander peoples experience significantly higher rates of cardiovascular disease, sudden cardiac death, and ventricular tachyarrhythmias compared to non-Indigenous Australians. Rheumatic heart disease (RHD), cardiomyopathy, and ischaemic heart disease are major contributors to this disparity.

Rheumatic heart disease (RHD)

Aboriginal and Torres Strait Islander peoples have among the highest rates of RHD globally (incidence up to 190 per 100,000 in the Northern Territory). RHD — particularly mitral valve disease — is a significant substrate for ventricular arrhythmias and SCD. The RHDAustralia programme (based at Menzies School of Health Research, Darwin) coordinates RHD register and secondary prophylaxis programmes.

Cardiomyopathy burden

Dilated cardiomyopathy and peripartum cardiomyopathy are more prevalent in Aboriginal and Torres Strait Islander communities. The Darwin Heart Failure Initiative has documented high rates of non-ischaemic cardiomyopathy in Top End communities. LV dysfunction assessment (echocardiography) should be prioritised in symptomatic patients.

Sudden cardiac death rates

Sudden cardiac death occurs at 2–3 times the rate in Aboriginal and Torres Strait Islander peoples compared to non-Indigenous Australians, and at younger ages. Many events occur in remote areas with limited access to emergency medical services and defibrillation.

Geographic barriers to electrophysiology

Electrophysiology services, catheter ablation, and ICD implantation are available only in capital cities and select regional centres. Patients in remote NT, WA, QLD, and SA may require interstate air transfer (RFDS) for procedures. Telehealth follow-up and remote ICD monitoring are critical for continuity of care.

AED access in remote communities

Public-access AED availability is significantly lower in remote Aboriginal and Torres Strait Islander communities compared to urban areas. Community AED programmes (St John Ambulance Australia, Heart Foundation) should be expanded. Training local community members in CPR and AED use is essential.

Cultural safety in arrhythmia care

Culturally safe care requires Aboriginal and Torres Strait Islander health workers and liaison officers in cardiac and EP departments. Sorry Business (bereavement obligations) may affect appointment attendance — flexible rescheduling is important. Family-based approaches to genetic counselling and cascade screening are preferred. Avoid deficit-framing; focus on strengths-based approaches and self-determination in health decisions.

Medication access and adherence

PBS Closing the Gap (CTG) co-payment measure provides PBS medicines at no cost or reduced cost for eligible Aboriginal and Torres Strait Islander peoples. Community-controlled health services (e.g., Aboriginal Medical Services — AMS) play a vital role in medication supply and adherence support. Remote communities may have limited pharmacy access — Continuous Quality Improvement (CQI) programmes through NACCHO support medication management.

Key organisations and pathways

RHDAustralia (Menzies School of Health Research) — RHD prevention and management. National Aboriginal Community Controlled Health Organisation (NACCHO). Heart Foundation Aboriginal and Torres Strait Islander heart health programmes. AIHW cardiovascular disease data. Closing the Gap Priority — cardiovascular disease management.

📚 References

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