Catecholaminergic Polymorphic Ventricular Tachycardia

Some patients are asymptomatic and identified only on family screening. When symptoms occur, they usually develop before the age of 10, with a mean age at presentation of 7 to 9 years (1). Boys tend to present at a younger age than girls (1, 2). Nevertheless, approximately 20% do not present until their third or fourth decade (2). The tachyarrhythmias may cause palpitations, syncope, or cardiac arrest. Events are typically triggered by emotional or physical stress. The disorder is a common cause of sudden death in young people, comprising about 10 to 15% of sudden cardiac death cases in the young (3), with a mortality risk of 30 to 50% by age 35 to 40 years (1, 4).

• Exercise testing

• Genetic testing

• Screening of first-degree relatives

Diagnosis should be considered in patients with unexplained cardiac arrest or syncope or a family history of such in the absence of structural heart disease.

Resting ECG is normal. Diagnosis is confirmed by exercise testing–induced polymorphic ventricular tachycardia (especially bidirectional ventricular tachycardia) that also reproduces the patient's symptoms. Genetic testing should then be performed; it has a yield of approximately 60% (1).

First-degree relatives of patients have a significant risk of disease as penetrance is high. They should have clinical evaluation (ie, to detect symptoms suggestive of arrhythmia) and exercise testing performed every 1 to 3 years. If the initial patient has a causative mutation identified, family members without the index mutation are then freed of the need for follow-up investigations.

• Exercise restriction

• Beta-blockade

• Flecainide

• Sometimes an implantable cardioverter-defibrillator (ICD)

• Sometimes left cardiac sympathetic denervation

All patients with CPVT have traditionally been advised to limit exposure strenuous exercise, competitive sports, and stressful environments given the catecholamine-sensitive nature of this disease (1, 2). However, some guidelines endorse a shared decision-making model, with competitive sports participation as a potential option for patients who are asymptomatic and do not have ventricular ectopy on exercise testing (either at baseline or with medical therapy or left cardiac sympathetic denervation) (3, 4). Athletes should be counseled on the need for appropriate precautions (eg, availability of an automated external defibrillator during training and competition).

For patients who have had symptoms (eg, syncope, cardiac arrest) or who have demonstrated ventricular fibrillation or sustained ventricular tachycardia, the primary treatment is high doses of a long-acting beta-blocker, preferably one that is non-selective and without intrinsic sympathomimetic activity (eg, nadolol, slow-release propranolol) (2).

For patients who are asymptomatic but carry a known causative gene for CPVT, beta-blocker treatment should be considered (2).

For patients with CPVT who survive an aborted cardiac arrest, an ICD, a beta-blocker, and flecainide therapy are recommended (2).

For patients who have not experienced an aborted cardiac arrest in whom exertional premature ventricular ectopy, presumed arrhythmogenic syncope, and/or polymorphic/bidirectional ventricular tachycardia occurs on maximal beta-blocker therapy, the addition of flecainide (for both its sodium channel and ryanodine receptor-blocking effects) should be considered (2). In such patients, if presumed arrhythmogenic syncope and/or polymorphic/bidirectional ventricular tachycardia persists, ICD placement should also be considered. Thereafter, whether left cardiac sympathetic denervation should be considered as a complementary therapy or be reserved for patients with frequent ICD discharges is unclear.

ICD therapy is complicated in these young patients, who tend to have more frequent inappropriate shocks and ICD-related complications than do patients who require ICD therapy in other settings (5). Furthermore, ICD shock therapies by virtue of their associated sympathetic discharge state may induce recurrent VT/VF (electrical storms) in patients with CPVT. These complications occur in up to 40% of patients with CPVT after a mean follow-up of 8 years.

Refractory cases may be treated with ablation of the polymorphic premature ventricular beats that induce VT/VF (6).

Follow-up typically involves repeated exercise testing, but the predictive value is only moderate.