EFFECTS OF POSTURE ON METABOLIC AND HEMODYNAMIC PREDISCHARGE EXERCISE RESPONSE AFTER ACUTE MYOCARDIAL-INFARCTION

Predischarge exercise testing after acute myocardial infarction (AMI) is an important noninvasive modality for risk stratification. To study the impact of position on cardiopulmonary exercise response, 30 patients performed symptom-limited upright treadmill and supine bicycle ergometry exercise an average of 8 days after an AMI. The exercise sequence was randomly assigned with a minimum 4-hour interval between tests. Exercise time and peak oxygen consumption were significantly greater in the upright position (7.0 ± 2.0 vs 5.6 ± 2.0 minutes; p < 0.001 and 14.9 vs 12.0 ml/min/kg; p < 0.001, respectively). Compared to the supine position, exercise in the upright position was associated wtih a significant increased incidence of ischemic exercise-induced ST-segment depression (33 vs 20%; p < 0.03), and chest pain (20 vs 10%; p < 0.04). Thus, position is an important determinant of myocardial ischemic response and exercise tolerance in patients who perform symptom-limited exercise tests early after AMI. © 1990.