USEFULNESS OF HEAVY ISOMETRIC-EXERCISE ECHOCARDIOGRAPHY FOR ASSESSING LEFT-VENTRICULAR WALL MOTION PATTERNS LATE (GREATER-THAN-OR-EQUAL-TO-6 MONTHS) AFTER ACUTE MYOCARDIAL-INFARCTION

The aim of this prospective study was to determine the effects of heavy isometric exercise on left ventricular (LV) wall motion patterns in patients who have had myocardial infarction, and to compare heavy isometric exercise with dynamic exercise for competence in eliciting LV wall motion abnormalities at equivalent rate-pressure products. Echocardiography was performed in 42 patients during supine bicycle ergometry and during heavy dynamometer stretching at 50% of maximal voluntary contraction. Systemic vascular resistance increased from 1,484 to 1,649 dynes s cm-5 (p <0.05) during isometric exercise, and decreased significantly during dynamic exercise. Wall motion abnormalities or new asynergy were induced by isometric exercise in 120 segments, 107 of which (89%) showed significant stenosis of the perfusing coronary artery. Hypokinesia was the dominant pattern in the range of 76 to 90% narrowing; akinesia was dominant at 91 to 100% narrowing. Wall motion abnormalities were also documented in 13 segments (11%) assumed to be supplied by vessels with nonsignificant stenosis. Dyskinesia, seen in 7% of the segments, was equally distributed between both groups with significant stenosis. Sensitivity and positive predictive value in identifying specific coronary vessel disease was similar for both isometric and dynamic exercise. In conclusion, heavy isometric exercise in patients who have had myocardial infarction induces wall motion abnormalities of a severity proportional to the degree of coronary narrowing. This exercise method is similar to dynamic exercise for ability in identifying obstructions in a specific vessel. Furthermore, when compared at near-equal rate-pressure products, heavy isometric exercise is far superior in sensitivity to dynamic exercise.