Transient bifascicular block during Prinzmetal's variant angina.

A 49-year-old man had bradycardia-hypotension syndrome and transient right bundle branch block with left anterior fascicular block during an attack of Prinzmetal's angina. Coronary arteriography showed 50 percent obstruction of the proximal left anterior descending artery; subsequently, he had subtotal occlusion at the stenotic portion with ergonovine administration. The occurrence of this conduction abnormality with Prinz metal's angina suggests that diminished blood supply of the proximal His-Purkinje system is the probable mechanism.