Importance of morphological changes in T-U waves during bepridil therapy as a predictor of ventricular arrhythmic event.

BACKGROUND Although bepridil is a useful anti-arrhythmic agent for atrial fibrillation, the appearance of serious ventricular arrhythmia, such as torsades de pointes, might be a problem. In this study, T-U wave morphology was evaluated during bepridil therapy and was examined as a predictor of ventricular arrhythmic events. METHODS AND RESULTS The study population consisted of 113 patients on bepridil therapy. They were divided into 2 groups with and without ventricular arrhythmic events. Morphological changes in T-U waves were analyzed in leads V(2-5). During bepridil treatment, the QTc interval was prolonged from 0.45+/-0.01 to 0.49+/-0.01 s(1/2) in all patients (P<0.0001) and any type of T-U wave change (fused U, slurred, bifid, biphasic or negative) appeared in 73% of event-free and 100% of event groups. In univariate analysis, QTc interval before bepridil (P=0.028), a wide QRS complex (P=0.042) before bepridil, biphasic (P=0.027) or negative (P=0.002) T-U waves in the stable phase, and the new appearance of biphasic (P=0.004) or negative (P<0.0001) T-U waves exhibited significant differences. In multivariate analysis, only newly appeared negative T-U wave exhibited a significant difference (odds ratio 10.13, 95% confidence interval = 0.031-2.302, P=0.041). CONCLUSIONS In patients with stable bepridil treatment, a change in T-U wave morphology might be a useful predictor of ventricular arrhythmia assisting the QT interval.