Exercise tolerance in late survivors of balloon pumping and surgery for cardiogenic shock
Intra-Aortic Balloon Pumping
Thirty-four patients underwent coronary bypass within 24 hours of balloon pumping instituted for cardiogenic shock that occurred within 96 hours of acute myocardial infarction. Criteria for diagnosis of cardiogenic shock were cardiac index less than 2.0 l/min/m 2, oliguria and systolic blood pressure less than 80 mm Hg on medical management. Bypass grafting to ischemic areas outside the zone of acute myocardial infarction was performed. At mean follow-up of 22 months, 16 patients (47%) were alive, including five of 14 (36%) with cardiogenic shock caused by myocardial infarction who also had ventricular septal defect or mitral regurgitation, and 11 of 20 (55%) with cardiogenic shock and no mechanical defect. Thirteen patients underwent exercise testing (modified Bruce protocol) at follow-up. Mean exercise capacity was 2.4 ± 0.6 minutes (± SEM) of stage II, with four patients reaching 2 minutes of stage III. End points of exercise were fatigue (six patients), dyspnea (three patients), chest pain (two patients), hypotension (one patient) and target heart rate (one patient). The group achieved a mean of 89 ± 2% of maximum predicted heart rate, with exercise-related blood pressure augmentation of 24 ± 4% in 12 of 13 patients. ST-segment elevation appeared at end-exercise in nine patients, in the area of prior Q-wave myocardial infarction. ST-segment depression occurred in four patients but was unrelated to symptoms; all patients were taking digitalis. Six patients returned to their former work activity. These data show substantial exercise capacity on follow-up of 13 patients treated with balloon pumping and bypass grafting after myocardial infarction.