Introduction: Recent experimental and clinical trials have provided evidence that increased duration of right ventricular electrogram in response to premature extrastimuli correlates with the risk of ventricular fibrillation in noncoronary heart disease. The aim of the present study was to investigate the duration of the surface QRS complex at short coupling intervals of extrastimuli as a new indicator for major arrhythmic events.
Methods: 32 patients all with nonischemic heart diseases and well preserved left ventricular function in sinusrhythm were included into the study. Fifteen had witnessed sudden death due to ventricular fibrillation or polymorphic ventricular tachycardia (VF/VT group). The control group comprised seventeen patients without a history of ventricular arrhythmias (control group). All subjects underwent programmed ventricular stimulation and QRS-durations S1-S2-S3 directly above the ventricular refractory period were analyzed.
Results: Both groups had a comparable basic QRS complex of 85 +/- 9 (VF/VT) vs. 87 +/- 13 ms (control), p = 0.83. The stimulated QRS complex S3 was significantly wider in the VF/VT group compared to the control group at pacing rates of 500 and 430 ms (500 ms: 256 +/- 22 vs. 235 +/- 32 ms, p = 0.04; 430 ms: 258 +/- 23 vs. 226 +/- 27 ms, p = 0.001). No differences with regard to the ventricular effective refractory period and the ventriculoatrial conduction could be observed beween the groups.
Conclusions: Our results indicate that the duration of the paced QRS complex may be a valuable parameter to predict arrhythmic risk in patients with nonischemic heart disease. Further prospective studies in larger trials are necessary to corroborate this investigation.