[The differential characteristics of early ventricular arrhythmias following a myocardial infarct in patients with and without ventricular fibrillation].

OBJECTIVE: To evaluate the characteristics of early ventricular arrhythmias in acute myocardial infarction and their predictive value of ventricular fibrillation.

PATIENTS AND METHODS: We retrospectively compared 85 patients who presented ventricular fibrillation with a control group of 187 consecutively acute myocardial infarction patients recorded within the first 12 hours after onset of acute myocardial infarction symptoms. Patients in Killip class III-IV were excluded.

RESULTS: In the ventricular fibrillation group we observed a high prevalence of inferior site of infarction (69 vs 56%; p < 0.05), sum of ST in 3 leads (ST-3 leads) with maximal elevation (13 +/- 17 vs 8 +/- 7 mm; p < 0.005), basic heart rate (97 +/- 23 vs 88 +/- 18 bpm; p < 0.01), R-on-T phenomenon (16 vs 2%; p < 0.001). In 22 patients in whom the ventricular fibrillation episode was registered, the basic heart rate preceding the ventricular fibrillation was fast (113 +/- 54 bpm), and the prematurity index (coupling interval/QT) shorter than in the other ventricular arrhythmias (0.9 +/- 0.2 vs 1.2 +/- 0.3 s respectively; p < 0.005). The prematurity index of ventricular arrhythmias in the ventricular fibrillation group was shorter than in the control group (1.2 +/- 0.3 vs 1.5 +/- 0.3 s respectively; p < 0.0001) and the heart rate during runs was faster (172 +/- 54 vs 126 +/- 40 bpm; p < 0.01). The logistic regression analysis showed that R-on-T phenomenon (odds ratio [OR] = 2.8), inferior site of infarct (OR = 3.65), sum of ST-3 leads > 10 mm (OR = 5.82), and basic heart rate > 100 bpm (OR = 2.33) were independent risk factors for ventricular fibrillation.

CONCLUSION: Characteristic ventricular arrhythmias were found to precede ventricular fibrillation episodes: R-on-T phenomenon or short prematurity index and fast runs of ventricular tachycardia, with other parameters such a inferior site of infarct, sum of ST-3 leads > 10 mm and basic heart rate > 100 bpm.