Nonsustained VT in the absence of apparent structural heart disease
- Robert Phang, MD, FACC, FHRS
Robert Phang, MD, FACC, FHRS
- Albany Associates in Cardiology
Nonsustained ventricular tachycardia (NSVT), defined as three or more consecutive ventricular beats at a rate of greater than 100 beats/min with a duration of less than 30 seconds (waveform 1), is a relatively common clinical problem . It is often asymptomatic and typically diagnosed during cardiac monitoring (eg, ambulatory monitoring or inpatient telemetry) or an exercise test performed for other reasons. If the patient is asymptomatic, the major clinical challenge is to determine if the NSVT is relatively benign or indicative of an increased risk of sudden cardiac death. A major determinant of prognosis in patients with NSVT is the presence or absence of underlying structural heart disease as diagnosed using other modalities (eg, echocardiography, exercise stress testing, cardiac computed tomography or magnetic resonance imaging). The 12 lead electrocardiogram should also be assessed in conjunction with imaging and is particularly important in screening for inherited channelopathies, as those conditions often have no apparent structural heart disease.
This topic will discuss NSVT in patients without apparent structural heart disease. NSVT occurring in patients with different forms of heart disease, as well as sustained VT in patients without apparent structural heart disease, are discussed separately. (See "Monomorphic ventricular tachycardia in the absence of apparent structural heart disease" and "Catecholaminergic polymorphic ventricular tachycardia and other polymorphic ventricular tachycardias with a normal QT interval".)
INCIDENCE OF NSVT
NSVT, with an incidence ranging from 0 to 4 percent in the general population, is more common with increasing age and more often occurs in men . These incidence figures are drawn from studies using prolonged recordings in relatively small numbers of normal subjects. It is likely, however, that a single 24-hour recording significantly underestimates the true frequency of this often asymptomatic and intermittent arrhythmia.
IDENTIFYING THE ORIGIN OF THE WCT
The initial challenge may be determining if the wide complex tachycardia (WCT) is truly of ventricular origin versus aberrantly conducted supraventricular beats. Aberrancy involves the premature activation of the bundle branches where one bundle conducts normally and the other is still refractory and therefore exhibits a typical bundle branch pattern, usually the right bundle branch block (RBBB). Various morphologic clues favor aberrancy, including:
●Visualization of a premature atrial contraction immediately preceding the WCT
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- INCIDENCE OF NSVT
- IDENTIFYING THE ORIGIN OF THE WCT
- SYNDROMES WITH FREQUENT NSVT
- Repetitive monomorphic ventricular tachycardia
- Idiopathic left ventricular tachycardia
- Nonsustained polymorphic ventricular tachycardia
- Arrhythmogenic right ventricular cardiomyopathy
- CLINICAL MANIFESTATIONS
- Exercise-induced NSVT
- SUMMARY AND RECOMMENDATIONS