Decreased QTc dispersion after coronary revascularization: relationships with the quantitative degree of improvement in myocardial ischemia

Abstract

Object and Methods: : : :Thirty-four patients (mean age:58.1±8.3 years, M:F=21:13 with angina in the absence of previous myocardial infarction, who underwent percutaneous coronary intervention (stenting and/or balloon PTCA, n=25 or coronary arterial bypass grafting (CABG, n=9 were evaluated to assess the relations- hips between the degree of improvement in myocardial dipyridamole Tl-201 SPECT and the degree of decrease in QTc dispersion after coronary revascularization. QTc dispersions were measured manually using digitizer by a single observer from ECGs printed at 25 mm/sec, 1 day before, immediately, 1 day, and 1 month after the revasc- ularization procedure. Myocardial Tl-201 SPECTs were performed before and 1 month after the revascularization and ischemic indices were measured in all cases. Results:Mean QTc dispersion was 51.4±17.0 msec before revascularization, 42.6±15.1 msec immediately after, 45.6±19.3 msec 1 day after and 37.4±11.6 msec 1 month after revascularization. The decrease of QTc dispersion immediate (p=0.001 and 1 month (p<0.001 after revascularization, were statistically significant. Mean Tl-201 SPECT ischemic index measured before the revascularization (7.8±5.9 was significantly higher (p<0.001 than the one measured 1 month after the revascu- larization (1.5±2.8. But, in Δischemic index (ischemic index before revascularization-ischemic index 1 month afer revascularization, there was no significant difference between the patients with decrease in QTc dispersion after revascularization (6.2±6.3, n=27 and the patients without decrease in QTc dispersion (6.6±5.2, n=7). There was no statistically significant correlation between Δ QTc (QTc dispersion before revascularization- QTc dispersion 1 month afer revascularization and Δischemic index in total subjects. Conclusion:QTc dispersions decrease after successful coronary revascularizations in patients with angina, but considering the relationships between the changes of QTc dispersions and ischemic indices in myocardial dipyridamole Tl-201 SPECT, the degree of decrease in QTc dispersion after coronary revascularization does not have the relationships with the quantitative degree of improvement in myocardial ischemia. (Korean Circulation J 2000;30(8 :998-1003