Background: The primary success of the coronary artery reperfusion by primary coronary intervention (PCI) is almost angiographically assessed by TIMI flow score. The perfusion at a microvascular level can be inadequate despite the restoring of normal flow in the epicardial coronary artery. One of the options of successful reperfusion at a microvascular level is the measurement of ST-segment resolution (STR) after primary PCI. Aim: The assessment of ST-segment resolution in patients indicated for primary PCI and the comparison with clinical data. Methods: The authors studied 149 patients (68.5 % men) with ST elevation acute myocardial infarction treated by primary PCI. The ECG was taken at the time of arriving patient at coronary unit and compared with ECG early after primary PCI. Patients were divided into 3 groups according to the grade of STR: with complete (> 70 %), partial (30 - 69 %) and none (< 30 %) STR. The lead with maximal changes (STEmax) and sum of ST elevation (STEsum) were assessed. Results: 42 (28.2 %) patients had complete STR, 55 (36.9 %) partial STR and 52 (34.9 %) patients didn’t achieve STR. STR was connected with better left ventricular ejection fraction, which was in group with complete STR 50 % compared with 39.4 % in group without STR (p < 0.0001). Patients with symptoms of heart failure on admission (Killip II - IV) had complete STR only in 4 cases (10 %) compared with patients without heart failure (Killip I), where was complete STR in 38 (34.8 %), (p = 0.003). There wasn’t noted significant difference in STR at dependence on glycoprotein IIb/IIIa inhibitors administration. A normal or mildly slower coronary flow (TIMI 2, 3) was achieved in 146 patients (98 %), 3 patients (2 %) had inadequate coronary flow after primary PCI (TIMI 0, 1). Conclusions: The evaluation of early ECG changes is simple method for the assessment of primary PCI success at the microvascular level. Our outcomes confirm a differences in achievement of optimal epicardial coronary flow and a perfusion at microvascular level.

        Key words: ST-segment resolution - Acute myocardial infarction - Primary PCI - Microcirculation