The electrocardiographic response to maximal treadmill exercise of asymptomatic men with left bundle branch block.

This study presents the results of maximal treadmill testing and coronary angiography in 31 asymptomatic USAF aircrewmen with acquired left bundle branch block. There were two subgroups: 26 men with normal coronary angiography and five men with significant angiographic coronary angiography and five men with significant angiographic coronary artery disease. The mean amount of maximal ST-segment depression induced by treadmill exercise was --0.5 mv. for both groups and the range in the normal subgroup was --0.3 to --1.0 mv. No significant differences were found between the groups. We concluded that apparently healthy, asymptomatic men with acquired left bundle branch block can have considerable ST-segment depression in response to maximal treadmill testing and that their ST-segment response cannot be used to make diagnostic decisions about them.