Amount of ST wave resolution in patients with and without spontaneous coronary reperfusion in the infarct -related artery after primary PCI: an observational study.

Objective: In patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI), a patent infarct-related artery (IRA) on initial angiography was associated with better angiographic results and improved prognosis compared with patients without spontaneous reflow. The role of systematic emergency PCI in patients with spontaneous reperfusion during myocardial infarction is debated. We compared the amount of ST wave resolution (STR) in patients with and without spontaneous coronary reperfusion (SCR) in the infarct related artery.

Methods: This study was designed as an observational cohort study. One hundred sixty-one consecutive patients (121 males, 40 females, with a mean age of 56±10 years) who had STEMI and treated with primary PCI without previous thrombolytic therapy were included in the study. All patients were treated with primary PCI within 12 hours from the onset of the symptoms and had stent implantation in the culprit lesion. ST wave resolution was measured as percent resolution of ST segment elevation from electrocardiogram (ECG), before and after PCI, classified as complete (>70%), partial (30% to 70%), or absent (<30%). SCR was defined as a TIMI grade III flow in the IRA on baseline coronary angiogram. The amount of ST wave resolution (STR) in patients with and without SCR in the IRA was compared. We used Chi-square test, Student's t-test and the Mann-Whitney U test for statistical analysis.

Results: At the baseline coronary angiography 40 (25%) patients had SCR and 121 patients (75%) had TIMI flow grade 0, 1 or 2 (non-SCR group). ST segment resolution amount was significantly higher in patients without SCR (53±17 versus 13±23 mm; p<0.001). In fact; in five patients whom had patent infarct related artery in initial angiography, ST segment elevation increased according to pre-PCI ECG.

Conclusion: Mean ST wave resolution was lower in patients with spontaneous coronary reperfusion who were treated with primary PCI compared to their counterparts who did not have spontaneous coronary reperfusion on initial coronary angiography.