1061Microvascular Obstruction in Patients with ST segment elevation MI-What is it relation to the clinical or presenting symptoms?

Objectives: Microvascular obstruction (MVO) demonstrated on cardiac MRI (CMR) following primary percutaneous coronary interventions (PPCI) is an independent predictor of adverse outcome in patients with ST segment elevation MI (STEMI). The purpose of this study was to determine demographic, clinical and angiographic correlates of MVO (on CMR) post PPCI for STEMI. Methods: The study comprised 60 consecutive patients who underwent PPCI for first STEMI within 12 hours of symptoms onset. CMR scans were performed 4 ± 1 days post PPCI. CMR was evaluated for left ventricular (LVEF), right ventricular ejection fractions (RVEF), presence and amount (gr) of delayed enhancement (DE) and MVO. The patients were stratified into 3 thirds based on the MVO/LV mass. Peak troponin levels were determined in all patients. Results: Patients in the upper third (mean MVO/LV mass =5.4 ± 2; N = 20) compared with the patients in the other two thirds (0.7 ± 0.8; N = 40) had larger extent of DE (27 ±10 gr VS. 17 ±12 gr; p < 0.01 ), lower LVEF ( 50% ±10 VS. 57% ±10%; p = 0.03 ), higher peak troponin value (131 ±96 VS. 40 ±33; p < 0.01 ) and numerically higher incidence of LV thrombus (16% VS. 2.6%; p = 0.09). Patients in the upper third were less likely to have an open infarct related artery (IRA) on the first angiography (16% VS. 53%; p = 0.04). Patients in the two study groups were similar with respect to their age, gender distribution, risk factors for CAD including diabetes and hypertension as well as angiographic extent of CAD and IRA distribution. There were also no significant differences in the clinical features including ischemic time, door to balloon time, initial infarct extent as manifested by the summation of ST – segment elevation. Conclusions: In STEMI patients undergoing PPCI, MVO (on CMR) extent was associated with indices of larger infarction, presence of LV thrombus and was less likely in patients with open IRA on initial angiogram.