Prediction of Cardiac Risk prior to Elective Abdominal Aortic Surgery: Role of Multiple Gated Acquisition Scan
Debate continues regarding the value of cardiac testing before major vascular surgery. Studies looking at whether a low radioisotope left ventricular ejection fraction (LVEF) could reliably predict postoperative cardiac events have produced conflicting results. Technetium-99m multiple gated acquisition (MUGA) scanning was employed in 122 patients undergoing elective abdominal aortic aneurysm surgery to estimate the resting LVEF and to detect regional or global myocardial wall motion abnormalities (WMAs). Adverse cardiac outcomes were predicted using logistic regression analysis. Among this group of patients, 20 did not proceed to surgery for a variety of reasons, and 102 underwent surgical repair. More than half of the patients (55%) had a history of cardiac disease. The mean ± SD LVEF was 55.5% ± 11.1%. Altogether, 31 patients had WMAs, and 21 had both WMAs and an abnormal LVEF (≤ 50%). Altogether, 20 cardiac complications were encountered in 17 patients (17%). Logistic regression analysis identified four significant predictors of cardiac complications: history of cardiac disease [odds ratio (OR) 10.43; 95% confidence interval (CI) 1.3 and 80.5], the presence of WMAs (OR 10.1, CI 1.4 and 74.6), additional procedures (OR 12.1, CI 1.4 and 103.0), and reoperation during the postoperative period (OR 6.4, CI 1.4 and 30.4). This is the largest reported British series of cardiac testing using MUGA scans prior to abdominal aortic reconstruction. Only the presence of WMAs (not the resting LVEF) was useful for predicting postoperative cardiac events. A history of cardiac disease, additional procedures, and reoperation during the postoperative period also place a patient at high risk for cardiac complications. A normal LVEF is by no means reassuring that a patient is at low risk of suffering an adverse cardiac outcome.