CPVT is a genetic arrhythmia syndrome causing adrenergically triggered polymorphic or bidirectional VT in structurally normal hearts. Suspect it in exertional syncope, especially in young patients with normal ECGs and family history of sudden death. The autopsy is usually inconclusive for cause of death, without genetic testing

Bidirectional VT or polymorphic VT during exercise or catecholamine challenge. Resting ECG is usually normal.

Most commonly autosomal dominant mutations in the RYR2 gene. Less commonly, autosomal recessive mutations in CASQ2. These affect calcium regulation in cardiac cells.

Resting ECG (usually normal), exercise stress test (diagnostic), Holter monitoring, genetic testing, and in some cases, epinephrine challenge under specialist care.

CPVT: Normal QT, triggered by stress/exercise, bidirectional VT.
LQTS: Prolonged QT, torsades de pointes, triggered by exertion or startle.
Brugada: ST elevation V1–V3, arrhythmias occur at rest or during sleep.

Give IV propranolol or esmolol. Avoid adrenaline. Consider IV flecainide. Stabilise and refer urgently to cardiology. ACLS if unstable.

Non-selective beta-blockers (propranolol or nadolol), flecainide for VT suppression, lifestyle changes to avoid triggers, and ICD in refractory cases or survivors of arrest.

In survivors of cardiac arrest or patients with VT/syncope despite medical therapy. Caution: ICD shocks can increase arrhythmia burden unless on beta-blockade.

Adrenergic agents (adrenaline, isoprenaline), sympathomimetics, stimulants (e.g., amphetamines). Avoid anything that increases catecholaminergic tone.

First-degree relatives should undergo exercise testing, ECG monitoring, and genetic testing if a known mutation is present in the proband. Genetic counseling is essential.

Drug-induced QT prolongation (ondansetron + droperidol) triggering torsades de pointes, a polymorphic VT associated with prolonged QTc.

Prolonged QTc (>460 ms in females) due to congenital ion channel defects or acquired causes (drugs, electrolyte disturbance).

LQT1 (KCNQ1), LQT2 (KCNH2), LQT3 (SCN5A)

LQT1: exercise/swimming
LQT2: sudden noises/stress
LQT3: sleep or rest

Droperidol, ondansetron, haloperidol, sotalol, erythromycin, citalopram. See crediblemeds.org.

Hypokalemia, hypomagnesemia, hypocalcemia — all increase early afterdepolarizations and torsades risk.

Polymorphic VT with waxing/waning QRS amplitude (“twisting” morphology), usually pause-dependent, triggered by prolonged QT.

Give IV magnesium sulfate 10mmol as a bolus and repeat as needed immediately. Stop QT-prolonging meds. If unstable, defibrillate. If recurrent, consider overdrive pacing.

THC may enhance sympathetic tone;Vomiting may cause hypokalemia, hypomagnesemia, ondansetron and droperidol block cardiac K+ channels (IKr), prolonging repolarization.

The Schwartz score — includes QTc, T-wave alternans, syncope, family history, and known gene mutation. ≥3.5 = high probability.

Beta-blockers (nadolol or propranolol) are first-line. Avoid QT-prolonging drugs. ICD for high-risk patients.

Patients with cardiac arrest, recurrent syncope despite beta-blockers, or very prolonged QTc (>550–600 ms)

Exercise testing, epinephrine QT stress test, Holter monitoring, and genetic screening.

12-lead ECG, consider Holter or treadmill test, and genetic testing if familial mutation identified. Educate on lifestyle and meds.

Syncope with exertion or emotion, seizures with normal neurology, family history of sudden death or prolonged QTc on ECG.