[Causes and prognosis of syncope in patients with primary dilated cardiomyopathy].

The causes of adverse prognosis of patients with primary dilated cardiomyopathy remain controversial. Classically, it is thought that syncope is associated with an increased risk of mortality. The aim of this study was to try and identify the causes and prognostic significance of syncope in patients with primary dilated cardiomyopathy. Sixty-five patients aged 31 to 80 with primary dilated cardiomyopathy were admitted for investigation of syncope. The average ejection fraction was 27 +/- 10%. Invasive and non-invasive investigations including complete electrophysiological investigations, were performed. Sustained monomorphic ventricular tachycardia was induced in 14 patients (21.5%), ventricular flutter or fibrillation was induced in 9 patients (14%), a supraventricular arrhythmia in 17 patients (26%), and a conduction defect alone or associated with another arrhythmia in 7 patients (11%). A pathological result of tilt testing was observed in 5 patients (8%). No cause of syncope could be demonstrated in 15 patients (23%). During follow-up (4 +/- 2 years) there was a mortality of 15% which was only correlated with the reduction in left ventricular ejection fraction. The authors conclude that there are many causes of syncope in primary dilated cardiomyopathy: ventricular arrhythmias represent only 35% of cases and do not impact on the prognosis; above all, left ventricular ejection fraction is the most important prognostic factor.