[Left anterior hemiblock induced by exertion, caused by diagonal arterial stenosis: apropos of a case].

The authors report the case of a patient who developed left anterior hemiblock and ST segment depression during exercise testing which regressed during the recovery period. Coronary angiography showed severe stenosis of the diagonal artery. This conduction defect did not recur after effective angioplasty of the stenosed artery, reflecting the ischaemic nature of this abnormality.