Noninvasive tests for risk stratification in major vascular surgery

Background: The predictive values of noninvasive tests versus perioperative cardiac events in patients undergoing major vascular surgery has not been definitively established. Patients and methods: According to clinical markers and left ventricular function at rest, 188 patients were assigned to the following groups: 40 low, 115 moderate and 33 high risk. They were then randomly submitted to dipyridamole (n = 64), dobutamine (n = 63) stress echocardiography and dipyridamole perfusion scintigraphy (n = 61). Results: No events were observed in low-risk patients, whereas 12 (10.4%) and 8 (24%) events in moderate- and high-risk categories occurred, respectively. Only the high-risk category, as a predictive variable, was significantly related to the onset of cardiac complications (p <0.05). A positive dipyridamole/dobutamine stress test was related to cardiac events, but multivariate analysis showed that only severity and extent of ischemia were the best predictors of events (p <0.01 for dipyridamole and p <0.005 for dobutamine). The presence of reversible, but not fixed, perfusion defects at scintigraphy was significantly related to perioperative events; at multivariate analysis, only > 3 reversible perfusion defects represented a strong predictor of events (p <0.05). Conclusions: Among subjects undergoing major vascular surgery, severity and extent of ischemia during dipyridamole/dobutamine stress echocardiography and presence of > 3 reversible perfusion defects are strong predictors of cardiac events, particularly in moderate-risk category of patients.