Non-sustained ventricular tachycardia (NSVT) is classified in a variety of ways, depending on the clinical situation. The two primary distinctions are whether the arrhythmia occurs in the presence or absence of structural heart disease, and whether or not the arrhythmia causes symptoms. The prevalence of NSVT is highest in patients with structural heart disease. NSVT in patients with heart disease rarely causes symptoms, but may be associated with increased total mortality and sudden cardiac death risk. However, sudden cardiac death risk is usually not elevated out of proportion to the increased total mortality risk, suggesting that NSVT is merely a marker of sicker patients, rather than having a mechanistic relation to arrhythmias causing cardiac arrest. Furthermore, no trial has demonstrated that suppression of NSVT reduces mortality. In contrast, patients with symptoms due to NSVT usually do not have underlying structural heart disease. In these patients, treatment may be necessary to relieve symptoms and improve quality of life. Appropriate treatment of NSVT in this setting also does not improve mortality, because NSVT in the absence of structural heart disease is not associated with increased mortality or sudden death risk (excepting patients with ion channelopathies, such as long QT syndrome). The exception to this rule is the recognition that ventricular dysfunction may be caused by frequent or incessant episodes of NSVT. In this case, treatment of the arrhythmia may not only improve symptoms, but presumably also improve survival.
Optimal Strategies for Mitigating Sudden Cardiac Death Risk in At-risk Patients with Structural Heart Disease
