IS CORONARY ANGIOGRAPHY NECESSARY FOR VASCULAR-SURGERY PATIENTS WHO HAVE POSITIVE RESULTS OF DIPYRIDAMOLE-THALLIUM SCANS

Purpose: Because dipyridamole thallium (DT) scanning is a useful predi ctor of perioperative cardiac events, a positive result of a DT scan i s frequently the basis for performing more invasive cardiac evaluation and for consideration for performing coronary revascularization proce dures before performing peripheral vascular surgery. The rationale for this approach has been that the treatment of anatomically significant coronary artery disease would lower the risk of performing a subseque nt vascular operation. However, the benefit of performing aggressive d iagnostic and therapeutic cardiac procedures in such patients remains unproved. To examine this issue, data from patients who underwent coro nary angiography because of thallium redistribution were compared with data from matched control subjects who underwent peripheral vascular operations without further cardiac evaluation. Methods: The medical re cords of 70 consecutive patients who underwent coronary angiography be cause of the presence of two or more segments of redistribution on DT scan were reviewed and compared with 70 other patients matched with re spect to age, gender, peripheral vascular operation, and number of seg ments of redistribution on DT scan who did not undergo additional card iac evaluation. Results: DT scans were performed on 934 preoperative p eripheral vascular surgery patients to help in the assessment of opera tive risk. Ischemic responses, defined as two or more segments of redi stribution, were observed in 297. Of these, 70 underwent cardiac cathe terization and 25 underwent coronary revascularization procedures. Adv erse outcomes affected 46% of the coronary angiography group and 44% o f the control group (p = NS). Patients who underwent coronary angiogra phy and were considered for myocardial revascularization had fewer car diac events with a subsequent vascular operation than did the control subjects. However, any possible benefit from invasive cardiac evaluati on was offset by the three deaths and two myocardial infarctions (MIs) that complicated the cardiac evaluation. There was no significant dif ference between the angiography group and the matched control subjects with respect to perioperative nonfatal MI (13% vs 9%), fatal MI (4% v s 3%), late nonfatal MI (16% vs 19%), or late cardiac death (10% vs 13 %). In long-term follow-up, MIs occurred later in patients who underwe nt coronary angiography than the control subjects (p = 0.049), but thi s difference was not associated with an improvement in the overall sur vival rate. Conclusions: The risks of extended cardiac evaluation and treatment did not produce any improvement in either the perioperative or the long-term survival rate. For most vascular surgery patients who have a positive result of a DT scan, coronary angiography does not pr ovide any additional useful information.