Evaluation of ventricular tachycardia with respect to syncope in patients with old myocardial infarction, dilated cardiomyopathy and no overt heart disease.

The incidence and the direct cause of syncope in ventricular tachycardia (VT) among patients with old myocardial infarction (OMI, n = 48), dilated cardiomyopathy (DCM, n = 18) and no evidence of heart disease (IVT, n = 43) were compared. The presence or absence of syncope in each patient was surveyed by a standardized questionnaire and a variety of electrocardiographic parameters for aggravating arrhythmias were measured. Syncope occurred in 19 of 43 OMI patients (40%), in 5 of 18 DCM patients (28%) and 6 of 43 IVT patients (14%) and significantly more often in OMI than IVT (p less than 0.01). Ventricular fibrillation (VF) was confirmed in 14 of the 19 OMI patients with syncope, in 3 of the 5 DCM patients with syncope and 1 of 6 IVT patients with syncope. The incidence of VF was significantly higher in OMI than in IVT (p less than 0.01). Mean VT cycle lengths (VTRR'm) in OMI patients with and without syncope were 0.35 +/- 0.07 sec and 0.42 +/- 0.10 sec, respectively (p less than 0.05). VTRR'ms in DCM patients with and without syncope were 0.43 +/- 0.10 sec and 0.42 +/- 0.10 sec, respectively (NS). VTRR'ms in IVT patients with and without syncope were 0.27 +/- 0.04 sec and 0.41 +/- 0.10 sec, respectively (p less than 0.01). The results show that the high frequency of VT rate was the main cause of syncope in IVT, while VF was the main cause of syncope in OMI.(ABSTRACT TRUNCATED AT 250 WORDS)