Purpose: This study assessed the usefulness of thallium stress testing as a predictor of perioperative cardiovascular risk in diabetic patients with end-stage renal disease undergoing cadaveric renal transplantation. Demographic factors influencing the exercise performance in these patients were also examined.
Patients and methods: The medical records of 189 consecutive patients with diabetic nephropathy who were evaluated for cadaveric renal transplantation were reviewed. Thallium stress testing was the initial examination of cardiovascular status in 141 patients. An adequate examination was one in which at least 70% of maximum heart rate was achieved. A thallium stress test was normal if there were no ST segment depressions on the electrocardiogram and no perfusion abnormalities on the thallium scan. Forty-four patients underwent cardiac catheterization as the initial evaluation (Group C) and four patients underwent transplantation without a formal cardiovascular evaluation (Group D).
Results: Sixty-four of the 141 patients undergoing thallium stress testing had an adequate and normal examination (Group A). The incidence of perioperative cardiac events in this group was 2%. Seventy-seven patients (Group B) had an abnormal (n = 41) or an inadequate (n = 36) thallium stress test and most (n = 61) then underwent coronary angiography. The use of beta-blockers was the only predictor of an abnormal or inadequate thallium stress test (10 of 64 versus 27 of 77, chi 2 = 6.66, p less than or equal to 0.025). Forty-three percent (26 of 61 in Group B) of patients with inadequate or abnormal thallium stress tests had significant coronary artery disease on cardiac catheterization. The perioperative risk of cardiac events was not different in Group A versus Groups B, C, and D combined. Survival of Group A and B patients was not different but was significantly longer than that of Group C patients (p less than 0.001). Thallium stress testing was less expensive than cardiac catheterization ($1,000 versus $4,000 to $5,000).
Conclusions: Thallium stress testing allowed 45% of patients to avoid cardiac catheterization before renal transplantation. Discontinuing beta-blockers before thallium stress tests may improve exercise performance. The risk of perioperative cardiac events after transplantation was low and not different among patient groups. The relatively low predictive value of thallium stress testing for significant coronary artery disease and perioperative cardiac events in diabetic patients with end-stage renal disease suggests the need for the development of a more cost-effective, noninvasive screening test for this patient population.