[Flecainide exercise induced left bundle branch with chest pain].

Ischaemia has been the suggested mechanism of simultaneous left bundle branch block and chest pain on effort with normal coronary angiography. This hypothesis is very controversial and was not the mechanism in the two new cases of this syndrome. The two patients in whom effort pain and left bundle branch block were observed had been treated for paroxysmal supraventricular tachycardia with flecaine. Withdrawal of the anti-arrhtymic resulted in the disappearance of this syndrome. In these cases, the ischaemic mechanism could be excluded without ambiguity. The flecaine was the only cause of rate-related LBBB by slowing conduction in the left bundle branch with no effects on coronary reserve. It would seem that LBBB alone was the cause of chest pain. The absence of coronary artery disease was confirmed in the first patient and the diagnosis was highly improbable in the second.