[ECG findings with poor prognosis. Bifascicular block as a warning sign in cases of syncope].

Of 517 emergency room admissions for syncope at four Stockholm hospitals, 36 (7 per cent) were found to be cases of bifascicular block. Of these 36 patients, 34 underwent ambulatory electrocardiography (ECG) in hospital, which showed significant arrhythmia to be present in three cases [high-grade atrioventricular block (n = 2), or sustained ventricular tachycardia (n = 1)]. After a mean follow-up of 32 months, eight more patients had developed high-grade atrioventricular block, and 13 patients had died (eight of them suddenly). It is concluded that patients with bisfascicular block constitute a high-risk category, and would benefit from thorough investigation, including an invasive electrophysiological study, in order to identify those at risk of progression to high-grade atrioventricular block or malignant ventricular arrhythmia.