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

Park, Sang Sun; Nam, Gi Byoung; Choi, Kee Joon; Lee, Cheol Whan; Hong, Myeong Ki; Park, Seong Wook; Park, Seung Jung; Shin, Jung Woo; Moon, Dae Hyuk; Kim, You Ho

Abstract

OBJECT & METHOD: Thirty-four patients (mean age: 58.1+/-8.3 years, M:F=1:13) with angina in the absence of previous myocardial infarction, who underwent percutaneous coronary intervention (stenting and/or balloon PTCA, n=5) or coronary arterial bypass grafting (CABG, n=) were evaluated to assess the relationships 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 25mm/sec, 1 day before, immediately, 1 day, and 1 month after the revascularization 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+/-17.0msec before revascularization, 42.6+/-15.1msec immediately after, 45.6+/-19.3msec 1 day after and 37.4+/-11.6msec 1 month after revascularization. The decrease of QTc dispersion immediate (p=.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 revascularization (1.5+/-2.8). But, in deltaischemic 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=7) and the patients without decrease in QTc dispersion (6.6+/-5.2, n=). There was no statistically significant correlation between deltaQTc (QTc dispersion before revascularization-QTc dispersion 1 month afer revascularization) and delta ischemic 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.