Key Points
- To examine the prognostic significance of ventricular tachycardia induced by the fourth extrastimulus in patients with post-myocardial infarct left ventricular dysfunction.
- Consecutive patients (n=432) with post-MI left ventricular ejection fraction ≤40% underwent electrophysiological studies.
- Inducible VT was assessed with one to four extrastimuli for risk stratification.
- The incidence of inducible VT was documented, and primary endpoint comparisons were made among groups based on ES.
- The incidence of inducible VT was 37.9% (n=164), with 24% (n=39) induced by ≤2 ES, 46% (n=75) by 3 ES, and 30% (n=50) by 4 ES.
- VT induced with the fourth ES had shorter cycle length (218 ms vs. 256 ms, P=0.01) and was more likely to be hemodynamically unstable (77% vs. 55%, P=0.05).
- After 3 years, primary endpoint rates were 28% for ≤2 ES, 28% for 3 ES, and 18% for 4 ES (P=0.31), compared to 5% for EP-negative patients (P<0.01).
Structured PICO
Does induction of ventricular tachycardia with a fourth extrastimulus predict arrhythmic events in patients with post-myocardial infarct left ventricular dysfunction?
PPopulation432 consecutive patients with post-myocardial infarct left ventricular dysfunction (LVEF ≤40%) undergoing electrophysiological studies for risk stratification.
IInterventionInduction of ventricular tachycardia with a fourth extrastimulus during electrophysiological study.
CComparatorInduction of ventricular tachycardia with less than or equal to three extrastimuli, or no inducible ventricular tachycardia (EP-negative).
OOutcomeArrhythmia (sudden death or spontaneous ventricular tachycardia/ventricular fibrillation) after 3 years.composite
In patients with post-MI LV dysfunction, ventricular tachycardia induced by a fourth extrastimulus carries a comparable arrhythmic risk to VT induced by fewer extrastimuli, and a significantly higher risk than in EP-negative patients.