Effect of dipyridamole on QT dispersion in vasospastic angina pectoris

Life-threatening ventricular arrhythmias have frequently been documented in patients with vasospastic angina. Moreover, the incidence of ventricular a rrhythmias has been closely associated with increased QT dispersion. Howeve r, the underlying mechanism responsible for this arrhythmogenesis has not b een clarified, The effects of dipyridamole and subsequent aminophylline adm inistration on QT dispersion were examined in 35 patients with vasospastic angina and 30 patients with atypical chest pain. None of the patients enrol led in this study revealed any significant stenosis in coronary angiography . QT dispersion during dipyridamole followed by aminophylline administratio n was compared between the 2 groups. The baseline QT dispersion was similar in both groups (vasospastic angina: 27 +/- 8 ms; atypical chest pain: 28 /- 7 ms). No significant changes in QT dispersion were observed in patients with atypical chest pain by dipyridamole (23 +/- 9 ms) and subsequent amin ophylline administration (23 +/- 5 ms). However, the Qi dispersion in patie nts with vasospastic angina increased significantly by dipyridamole adminis tration (53 +/- 14 ms, p < 0.0001) and returned to baseline by subsequent a minophylline administration (26 +/- 10 ms). Our data suggest that the dispa rity of ventricular repolarization in vasospastic angina may be mediated by increased endogenous adenosine. (C) 1999 by Excerpta Medica, Inc.