Concerning Ventricular Tachycardia

Definition and Classification

Ventricular tachycardia (VT) is considered concerning when it is sustained (lasting >30 seconds) or causes hemodynamic compromise requiring termination in <30 seconds, regardless of the number of beats, as defined by the European Society of Cardiology 1
VT is defined as a cardiac arrhythmia of ≥3 consecutive complexes originating in the ventricles at a rate >100 bpm (cycle length <600 ms), according to the European Heart Journal and Circulation 1, 2
Nonsustained VT (NSVT) is defined as ≥3 beats in duration, terminating spontaneously in less than 30 seconds, as stated by the European Heart Journal and Circulation 1, 2
Sustained VT is defined as VT lasting >30 seconds or requiring termination due to hemodynamic compromise in less than 30 seconds, as defined by the European Heart Journal and Circulation 1, 2

Short bursts (fewer than 5 beats) of nonsustained VT are frequently seen but generally not associated with increased risk of sustained VT or VF, as reported by the Journal of the American College of Cardiology 3
NSVT becomes more concerning in specific clinical contexts, such as in patients with left ventricular ejection fraction ≤40%, NSVT 4 days or more after myocardial infarction with inducible VF or sustained VT at electrophysiological study, which may warrant ICD therapy, according to the European Heart Journal and Circulation 2, 4
NSVT in patients with structural heart disease, particularly with reduced ejection fraction, carries higher risk, as stated by Circulation 2

The clinical significance of VT depends not only on duration but also on hemodynamic stability during the arrhythmia, underlying cardiac disease, and symptoms during the episode, as reported by the European Heart Journal and Circulation 1, 2
VT can present with varying symptoms, including presyncope or syncope, which indicates hemodynamic compromise, as defined by the European Heart Journal 1

VT in patients with structural heart disease carries higher risk, and sustained VT with severe hemodynamic compromise is a Class I indication for ICD therapy, as stated by the European Heart Journal 4
Sustained VT without hemodynamic compromise but with LVEF ≤40% is a Class II indication for ICD therapy, according to the European Heart Journal 4
Nonsustained VT with LVEF ≤40% and inducible VF/sustained VT at EP study is a Class II indication for ICD therapy, as reported by the European Heart Journal 4

Post-MI patients are at highest risk for ventricular arrhythmias at presentation, with risk declining over hours and days, as reported by the Journal of the American College of Cardiology 5
VT occurring >48 hours after MI in the absence of ongoing ischemia may warrant ICD implantation, according to the Journal of the American College of Cardiology 5