T-wave abnormalities of intermittent left bundle-branch block.

Ischemia is traditionally considered a cause of intermittent left bundle-branch block (LBBB), and some patients have right precordial T-wave inversion in the normally conducted beats. Clinical correlates of T-wave abnormalities were examined in 46 consecutive patients with intermittent LBBB. Thirty-three patients (72%) had at least transient right precordial (V-14) T-wave inversion suggesting ischemia in normally conducted beats. Seventeen such patients had no evidence of coronary heart disease, including five with normal arteriograms. During LBBB conduction, T-wave abnormalities (upright T-waves I, aVL, V5-6) were frequent (48%) and more common than among patients with permanent LBBB (p less than 0.005). The T-wave abnormalities during LBBB conduction occurred in the absence of coronary heart disease in nine patients, including two with normal arteriograms. Thus, right precordial T-wave inversion may result from recent LBBB itself, associated with T-wave abnormalities during the LBBB, in the absence of coronary artery disease.