EARLY ASSESSMENT OF CORONARY RESERVE AFTER BYPASS-SURGERY BY DIPYRIDAMOLE TRANSESOPHAGEAL ECHOCARDIOGRAPHIC STRESS TEST

The evaluation of coronary reserve within a few hours of aortocoronary bypass surgery could be of extreme utility for the follow-up or therapeutical management of these patients. In 11 men patients who underwent aortocoronary bypass surgery, a dipyridamole echocardiography stress test was carried out before (1 to 3 days), early after (68 to 130 minutes), and 1 week after surgery. The first and third tests were performed using a standard transthoracic approach, while the second was performed by a transesophageal approach. Dipyridamole was administered intravenously at a dose of 0.56 mg/kg body weight (low dose) and eventually adding 0.28 mg/kg body weight (high dose), always in the absence of antiischemic therapy. An arbitrary wall motion score (0 = eukinesia; 1 = hypokinesia; 2 = akinesia; 3 = dyskinesia) was assigned to the seven different myocardial regions in which the left ventricle was divided in order to have a semiquantitative score. Under basal conditions wall motion score per patient in the three series of tests did not change significantly (1.6, 1.4, and 1.5, respectively), while the mean score during dipyridamole administration showed significant differences (3.6, 1.9, and 1.9, respectively), indicative of the results obtained by surgical repair. The test, positive in all patients before surgery, showed wall motion abnormalities and ischemic ECG changes in two patients immediately after surgery by the transesophageal approach. One patient who had a normal basal contraction pattern and an abnormal response after the test developed in the following days a perioperative myocardial infarction, while a second patient in the follow-up period developed low-level effort angina. Furthermore, by the transthoracic approach it was possible to document in three patients the reversibility of myocardial contraction abnormalities seen under basal conditions, the so-called "hibernating phenomenon." It is worthwhile to stress that the results obtained by the test performed 1 week after surgery were the same as those obtained 2 hours after surgery, indicating that the changes in coronary circulation have stabilized by the early hours after surgery. In conclusion, our data, although preliminary, demonstrate that with the transesophageal approach it is possible to evaluate the changes induced by coronary bypass surgery even in the early phases, allowing better patient management and permitting risk stratification. © 1990.