Investigations Effects of Early Thrombolytic Therapy on Left Ventricular Remodeling in Acute Myocardial Infarction

Following thrombolysis in acute myocardial infarction (AMI), the patency of infarct-related artery has been claimed to have additional effects on ventricular volumes more than salvaging the jeopardized myocardium. To scrutinize this "open artery hypothesis", we evaluated 42 initial anterior AMI cases with left anterior descending coronary artery (LAD) involvement who have been given streptokinase early. Angiographically the patients have been divided into two groups according to the patency of infarct related artery. Left ventricular volumes and ejection fractions (EF) have been calculated from the projections of left ventriculograms in RAO-30 degree position, using single plane area-length ellipsoid method. Infarct sizes (IS) have been derived from the number of ventricular radii of which the fractional shortenings were 2 standard deviations lower than the mean values of normal individuals. While IS values, end-systolic and end-diastolic volumes were significantly reduced in those with attained reperfusion of LAD (p<0.01, p<0.001, p<0.001, respectively), EF and pressures did not differ notably (p>0.05, p>0.2, p>0.3). It may be considered that early reperfusion reduces infarct expansion since there is a significant linear correlation between left ventricular volumes and IS. However, when IS is more than 5 radii, patients with patent arteries have smaller end-systolic volume indices (p<0.02), although IS values are similar (p>0.1). Hence, these findings suggest that early reperfusion of infarct-related artery, beyond salvaging the myocardium, reduces ventricular cavities which may reflect the prognosis better than EF.