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The predictive value of dipyridamole-thallium scintigraphy for cardiac risk assessment before major vascular surgery.

BACKGROUND
We prospectively examined the ability of dipyridamole thallium scintigraphy (DTS), as a preoperative screening test, to predict postoperative cardiac complications in patients undergoing peripheral arterial operations.


METHODS
From November 1993 to November 1995, a DTS study was routinely performed preoperatively in 167 consecutive patients who underwent arterial operations in our hospital. The clinicians were blinded to DTS results. The type of operation was: carotid endarterectomy (n = 53), abdominal aortic aneurysm repair (n = 45), aortobifemoral bypass (n = 31), femoropopliteal bypass (n = 32) and others (n = 6). Clinical and scintigraphic data were collected and analyzed uni- and multivariantly in order to identify those variables that correlate with postoperative cardiac complications.


RESULTS
Fifteen adverse cardiac events (three deaths, five myocardial infarctions, seven unstable anginas) occurred postoperatively among 167 patients (mortality: 1.8%, morbidity: 7.2%). Forty-four patients (26.3%) had a normal scintigraphic study, sixty (35.9%) had fixed defects and sixty-three (37.7%) had reversible defects. The most powerful predictive factors of cardiac complications in the multivariate analysis were the synchronous existence of three markers of coronary artery disease (angina pectoris, previous myocardial infarction, Q sign on ECG) and the presence of a reversible defect in the anterior segment of the left ventricle on DTS study.


CONCLUSIONS
This study demonstrates that the careful and detailed clinical examination is of paramount importance in detecting "high risk" patients and that DTS should be performed as a supplementary test since it offers significant information and further classifies patients of intermediate risk to develop postoperative cardiac complications.