Respective role of sympathetic tone and of cardiac pauses in the genesis of 62 cases of ventricular fibrillation recorded during Holter monitoring.

Sixty-two Holter recordings of sudden death due to ventricular fibrillation (VF) were analysed by full disclosure and computerized processing. Thirteen sudden deaths were due to torsades de pointes in noncoronary subjects (11/13), related to quinidine-like drugs and/or hypokalaemia: they were always initiated by a long RR cycle due to a post-extrasystolic pause, and announced by a progressive decrease of mean heart rate (from 77.5 +/- 2.5 to 60.6 +/- 2.7 beats min-1, P less than 0.001), in the three preceding hours. The other cases occurred in coronary patients (45/49), with acceleration of ventricular tachycardia (VT), monomorphic in 24 cases, polymorphic in 13, the ventricular rate increasing from 220.6 +/- 55 to 241.5 +/- 69 beats min-1, rather than with primary VF (12 cases). A cardiac pause (RR cycle exceeding 125% of the mean five preceding cycles) was present in 22/49 cases immediately before the onset of VT/VF. The coupling interval of the extrasystole initiating VT/VF was shorter than the shortest value encountered before: 377.6 +/- 94.5 ms vs 421.4 +/- 92.3. The prematurity index (coupling interval/preceding RR cycle ratio) was lower in primary VF than in VT leading to VF. In the last hour preceding VF, ST changes were unusual (five cases), whereas heart rate increased from 82.8 +/- 20 to 92.0 +/- 26.7 beats min-1, (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)