Exercise training after anterior Q wave myocardial infarction: importance of regional left ventricular function and topography

Abstract

To determine whether the extent of left ventricular dysfunction and the degree of shape distortion can predict outcome in survivors of moderate-sized anterior Q wave myocardial infarction who are undergoing exercise training, these variables were measured by two-dimensional echocardiography before and after 12 weeks of a low level exercise training program starting 15 weeks after infarction in 13 patients (7 in group 1 and 6 in group 2) and 12 weeks apart in 24 matched control patients without training. By the end of training, the functional class score had increased in group 2 (from 2.25 to 2.67, p less than 0.005) but had not changed in group 1. Further discrimination of groups 1 and 2 was provided by an initial asynergy (akinesia or dyskinesia, or both) less than 18% or greater than or equal to 18%. Compared with group 1, group 2 had greater initial asynergy (32 versus 6%, p less than 0.001), expansion index (asynergic/normal endocardial segment length: 1.8 versus 1.6, p less than 0.025) and peak shape distortion index (12.2 versus 1.0 mm, p less than 0.005) but lower ejection fraction (43 versus 59%, p less than 0.05) and thinning ratio (asynergic/normal wall thickness: 0.61 versus 0.74, p less than 0.05). These variables did not change with training in group 1. However, in group 2, training caused significant increase in asynergy (from 32 to 40%, p less than 0.05), expansion index (from 1.8 to 2.0, p less than 0.01) and peak shape distortion (from 12.2 to 20.9 mm, p less than 0.05) associated with a decrease in thinning ratio (from 0.61 to 0.51, p less than 0.001) and ejection fraction (from 43 to 30%, p less than 0.005). Initial values for these variables were similar for corresponding control groups but did not change over the 12 weeks. Thus, patients with greater than or equal to 18% left ventricular asynergy on the initial echocardiogram showed more shape distortion, expansion and thinning before exercise training and developed further functional and topographic deterioration with training.