Effect of the stenosis location and severity on left ventricular function after single-vessel anterior wall myocardial infarction.

Background The purpose of the current study was to determine how the location of the infarct-related lesion (IRL) and the degree of stenosis during the acute and chronic phases of infarction might affect left ventricular (LV) function in patients with acute anterior wall myocardial infarction. Methods Ninety consecutive patients with a first single-vessel anterior wall myocardial infarction (male/female ratio 75:15, mean age 60 ± 9 years) underwent coronary angiography (CAG) immediately and 1 month after infarction. Patients were grouped according to IRL location (proximal [Coronary Artery Surgery Study (CASS) No. 12] or distal [CASS No. 13] to the first diagonal branch of the left anterior descending artery) and according to the severity of stenosis at 1 month (severe stenosis [IRL >75%] and mild stenosis [IRL ≤75%]). At the time of infarction and 1 month and 1 year after infarction, total wall motion index (TWMI), left ventricular end-diastolic dimension (LVDd), left ventricular end-systolic dimension (LVDs), and fractional shortening (FS) were determined. Results TWMI was greater and FS was lower for CASS No. 12 lesions than for CASS No. 13 lesions. CASS No. 12 lesions were associated with a greater LVDd at 1 year and a greater LVDs throughout 1 year of observation. The patients with mild stenoses had significant improvements in TWMI and FS over time, whereas those with severe stenoses showed no improvement. Multivariate analysis showed that the independent factors predicting left ventricular function were IRL location at CASS No. 12, initial TIMI 0-1 flow in the IRL at emergency coronary artery graft, and the presence of a severe stenosis at 1 month. Conclusions In patients with severe stenoses at 1 month at CASS No. 12, left ventricular functional recovery is delayed and the left ventricular chamber is enlarged. In patients with CASS No. 13 lesions, left ventricular function is preserved well, regardless of the severity of residual stenosis. (Am Heart J 2001;141:55-64.)