Sustained ventricular tachycardias

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Primary prevention of ventricular arrhythmia is best accomplished by treating risk factors for coronary artery disease and left ventricular systolic dysfunction, including smoking cessation and management of hypertension and hyperlipidemia. Additional preventive measures include optimization of medical treatment of systolic dysfunction with medications such as ACE inhibitors/angiotensin receptor blockers, beta-blockers, and aldosterone antagonists. In patients with hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and the long QT syndrome, strenuous physical exertion should be avoided as exercise can provoke arrhythmias in these populations.

In addition, owing to the unpredictable and life-threatening nature of sustained ventricular tachycardias (VTs), primary prevention is critical in high-risk patients and can be accomplished through implantation of a prophylactic implantable cardioverter defibrillator (ICD). Traditionally, ICDs have been implanted with a transvenous lead. However, a subcutaneous ICD, where the ICD lead remains extravascular, is also an option. An approved version involves an ICD lead tunneled subcutaneously near the inferior border of the left rib cage and then up along the sternum, with the ICD generator located in the left axillary region.[19] Another extravascular ICD, involving a lead placed under the sternum, is being investigated.[20]

Patients at high risk include those with:

Ischemic or nonischemic cardiomyopathy (left ventricular ejection fraction [LVEF] ≤35%) and mild-to-moderate congestive heart failure symptoms (New York Heart Association class II or III symptoms). Those with severe heart failure (class IV) are at high risk as well, but have progressive heart failure as a competing mode of death, and thus should be considered for ICD only if they are candidates for cardiac resynchronization therapy

Ischemic cardiomyopathy (LVEF ≤40%) with nonsustained VT and inducible sustained VT during electrophysiologic testing

Ischemic cardiomyopathy (LVEF ≤30% and New York Heart Association class I symptoms)

Hypertrophic cardiomyopathy (HCM) with high-risk features such as family history of sudden death from HCM; massive left ventricular hypertrophy (wall thickness ≥30 mm); unexplained syncope; left ventricular systolic dysfunction; left ventricular apical aneurysm; extensive late gadolinium enhancement on cardiovascular magnetic resonance imaging; or frequent, longer, and faster runs of nonsustained VT.[8][9] Other clinical features that are utilized in calculating sudden cardiac death risk in HCM include age, left atrial diameter, left ventricular outflow tract obstruction, and exercise blood pressure response

Congenital arrhythmia syndromes, including symptomatic patients with long QT syndrome, Brugada syndrome, and catecholaminergic polymorphic VT with high-risk features.

One large cohort study found that the risk of first and recurrent life-threatening ventricular arrhythmias following ICD placement was significantly lower in women than in men. This suggests that a sex-specific risk assessment for prophylactic ICD placement may be beneficial. However, further research to better understand the sex differences driving these findings is warranted.[21]

Secondary prevention

In general, compliance with prescribed antiarrhythmic medications should help lessen the burden of ventricular arrhythmias. Patients with ischemic ventricular tachycardia should explore the feasibility of revascularization therapy.

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