980-91 Predictors of Thrombus Formation After Anterior Myocardial Infarction: Evidence of Protective Effect of Mitral Regurgitation

Abstract

It has been shown that mitral regurgitation (MRI prevents thrombus (T) formation in pts with dilated cardiomyopathy. Also, the relationship between low velocity ventricular flow and T formation after MI was recently demonstrated. However, no clinical study has shown that MR has independent effect on T formation in acute myocardial infarction (MI). In order to determine predictors of T after anterior MI, we have analyzed clinical (age, sex, Killip class, thrombolysis, peak CK values), echocardiographic (left ventricular end-diastolic volume index-EDVi, end-systolic volume index-ESVi, ejection fraction-EF, wall motion score index-WMSi, apical wall motion abnormalities, presence of MR) and angiographic (extent of coronary artery disease-CAD, patency of infarct related artery-IRA) variables in 54 consecutive pts with anterior MI. Two-dimensional and Doppler echocardiographic examinations were performed in the following sequence: day 1, day 2, day 3, day 7, after 3 and 6 weeks, 3 and 6 months and 1 year following MI. Pts with and without T were similar regarding age, sex and antithrombotic therapy. According to Cox's regression model p < 0.1 was considered significant T was detected in 31/54 pts (30/31 in the first week after Mil. Univariate analysis showed that T was associated with Killip class > 1 (beta = 0.6, p = 0.01), larger initial EDVi (beta = 1.7, p = 0.04) and ESVi (beta = 2.3, p = 0.002) and higher WMSi (beta = 0.7, p = 0.02). According to Cox's proportional regression model, significant independent predictors of T after MI were: high peak CK values (beta = 4.1, p = 0.06), initial EF ≥040% (beta = -0.8, p = 0.07), absence of MR (beta = -0.6, p = 0.06), and multivessel CAD (beta = 0.5, p = 0.06). Our data demonstrate that T after anterior MI is associated with large infarcts, poor left ventricular function and multivessel CAD. Since the absence of MR is also associated with T. it appears that MR may have protective effect on T formation after anterior MI.