Primary ventricular fibrillation was seen in 20 of 450 consecutive patients (4.4%) admitted within 24 hours after the onset of acute myocardial infarction. Compared with patients without primary ventricular fibrillation, they showed a lower mean age group and a higher incidence of anterior infarction. Warning ventricular arrhythmias preceded primary ventricular fibrillation in 58 per cent of cases. However, warning arrhythmias were also present in 55 per cent of patients without primary ventricular fibrillation. The following mechanisms of initiation of primary ventricular fibrillation were seen. 1) In one patient it was initiated by supraventricular premature beats showing aberrant intraventricular conduction. 2) In 2 patients, ventricular tachycardia degenerated into primary ventricular fibrillation. 3) In 17 patients, it was initiated by a ventricular premature beat; in 10 of these, the premature beat showed early coupling (RR'/QT<1 - the R on T phenomenon). However, ventricular premature beats showing the R on T phenomenon were also observed in 49 per cent of patients without primary ventricular fibrillation. In 7, primary ventricular fibrillation was initiated by a late coupled ventricular premature beat (RR'/QT>1); in 2, the very late coupling resulted in a ventricular fusion beat. The study suggests that warning arrhythmias and the R on T phenomenon are poor predictors of primary ventricular fibrillation in acute myocardial infarction. The observation that 41 per cent of primary ventricular fibrillation was initiated by a late coupled ventricular premature beat suggests that ventricular vulnerability during acute myocardial infarction may extend throughout most of the cardiac cycle and is not necessarily confined to the QT interval.
|Original language||English (US)|
|Number of pages||8|
|Journal||British heart journal|
|State||Published - Dec 1 1976|
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine