Increased QT dispersion in patients with vasospastic angina.
BACKGROUND
The risk factors for ventricular arrhythmias in patients with coronary vasospasm have not been identified. We evaluated QT dispersion in patients with vasospastic angina and its relation to susceptibility to ventricular arrhythmias during myocardial ischemia and reperfusion.


RESULTS
We assessed the corrected QT (QTc) dispersion before induction of coronary artery spasm by intracoronary injection of acetylcholine (baseline) and 30 minutes after administration of isosorbide dinitrate in 50 patients with vasospastic angina and 50 patients with atypical chest pain. The baseline QTc dispersion was significantly greater in patients with vasospastic angina than in patients with atypical chest pain (mean+/-SD: 69+/-24 versus 44+/-19 ms, 95% confidence interval of mean difference [CI]: 16 to 33 ms; P<0.001). QTc dispersion decreased significantly, to 48+/-15 ms (CI: 15 to 26 ms; P<0.001 versus baseline), after administration of isosorbide dinitrate in patients with vasospastic angina but did not change significantly in patients with atypical chest pain (mean+/-SD: 41+/-17 ms, CI: -3 to 9 ms). During the provocation test, 24 of 50 patients with vasospastic angina experienced ventricular arrhythmias. The baseline QTc dispersion was significantly greater in patients with than without ventricular arrhythmias (mean+/-SD: 77+/-23 versus 61+/-19 ms, CI: 4 to 26 ms; P<0.05).


CONCLUSIONS
Patients with vasospastic angina exhibited an increased baseline QTc dispersion compared with patients with atypical chest pain, which suggests that inhomogeneity of repolarization and susceptibility to ventricular arrhythmias are increased in patients with vasospastic angina, even when asymptomatic. The association between increased QTc dispersion and ventricular arrhythmias during the provocation test suggests that measurement of QT dispersion may help predict which patients with vasospastic angina are at high risk for ventricular arrhythmias during ischemia.
Suzuki
M
M
Department of Cardiology, Yokohama Minami Kyosai Hospital, Kanagawa, Japan.
Nishizaki
M
M
Arita
M
M
Ashikaga
T
T
Yamawake
N
N
Kakuta
T
T
Numano
F
F
Hiraoka
M
M
D000109:Acetylcholine; D000368:Aged; D000704:Analysis of Variance; D000787:Angina Pectoris / Q000150:complications / Q000175:diagnosis*; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology; D002637:Chest Pain / Q000150:complications / Q000175:diagnosis; D016009:Chi-Square Distribution; D016001:Confidence Intervals; D017023:Coronary Angiography / Q000379:methods; D003329:Coronary Vasospasm / Q000150:complications / Q000175:diagnosis*; D015716:Electrocardiography, Ambulatory / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007548:Isosorbide Dinitrate; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D014665:Vasodilator Agents
D014665:Vasodilator Agents; D007548:Isosorbide Dinitrate; D000109:Acetylcholine