Impact of myocardial blush grade on Tpe interval and Tpe/QT ratio after successful primary percutaneous coronary intervention in patients with ST elevation myocardial infarction

INTRODUCTION: Myocardial perfusion, when assessed by myocardial blush grade (MBG) is an independent predictor of major adverse cardiac outcomes. The terminal part of repolarization, measured as the interval from the peak to the end of the T wave (Tpe), is a relatively novel indicator of ventricular arrhythmias. The relations between MBG and Tpe interval have not been examined before. We aimed to evaluate the relationship between MBG and Tpe and Tpe/QT ratio after successful primary percutaneous coronary intervention (PCI) in acute ST-segment elevation myocardial infarction (STEMI). PATIENTS AND METHODS: In this study, 149 consecutive patients with STEMI and underwent primary PCI were included. The Tpe interval was defined as the interval from the peak of T wave to end of T wave, and measurements were performed from precordial leads on ECGs at admission and 90 minutes after revascularization. Patients with no myocardial blush were graded as MBG 0, those with minimal myocardial blush were graded as MBG 1, those with moderate myocardial blush were graded as MBG 2 and patients with normal myocardial blush were graded as MBG 3. RESULTS: Comparisons were made between the MBG 0-1, MBG 2 and MBG 3 groups. In all groups, post-procedural Tpe interval were significantly shorter than pre-procedural Tpe intervals (for all groups p<0.001). Post-procedural Tpe interval in MBG 3 group was significantly shorter than MBG 0-1 and MBG 2 groups (Tpe=81 +/- 11 ms in MBG 0-1 group, 81 +/- 11 ms in MBG 2 group and 72 +/- 10 ms in MBG 3 group; p<0.001, for all groups). Post-procedural Tpe/QT ratios decreased in all three MBG groups (p<0.001, for all groups). Tpe/QT ratios were smaller with the increasing MBG (p<0.001). CONCLUSIONS: Tpe interval and Tpe/QT ratio are closely associated with MBG after successful primary percutaneous coronary intervention in STEMI.