Effect of primary percutaneous coronary intervention on myocardial repolarization

We aimed to investigate the effect of coronary perfusion on QT interval dispersion in patients with acute myocardial infarction (MI).

Seventy-seven consecutive patients who had undergone primary percutaneous coronary intervention (PCI) for a first ST segment elevation MI during the first 12 h of symptom onset were included in the study. After achievement of thrombolysis in MI (TIMI) 3 flow of the infarct-related artery, corrected TIMI frame count (cTFC) and TIMI myocardial perfusion grade (TMPG) were measured. ECGs were performed in the following manner: at baseline, within 1 h after completion of the procedure, 24 h after the procedure and 48 h after the procedure. The corrected QT dispersion (QTd) and ST segment resolution (STR) were calculated.

There was a difference between the durations of corrected QTd (cQTd) before PCI and cQTd just after PCI. On the first day, cQTd before PCI was significantly more prolonged (52.3 ± 80 vs. 41.5 ± 49, P = 0.05) than cQTd on second day (52.3 ± 80 vs. 37 ± 50, P = 0.001). In the correlation analysis conducted among the durations of cQTd, cTFC and TMPG, no significant association was established. STR was, however, inversely correlated with duration of cQTd.

Our study results demonstrated that primary percutaneous coronary intervention leads to progressive shortening of QT dispersion in successful reperfusion, even in reduced cTFC.