Background: Non-invasive detection of coronary artery disease in dialysis patients, a major cause of mortality, often remains difficult. The aim of the study was to test the diagnostic and prognostic accuracies of combined dipyridamole-exercise thallium imaging in dialysis patients.
Methods: Dipyridamole-exercise thallium imaging and coronary angiography were both performed prospectively in 60 asymptomatic hemodialysis patients who were followed up, long term, by recording any major coronary event.
Results: Coronary angiography was abnormal in 13 patients (21%), and there was abnormal thallium uptake in 17 patients. Sensitivity, specificity, positive and negative predictive values, and overall accuracy of thallium to detect a coronary artery disease were 92, 89, 71, 98 and 90%, respectively. After a median follow-up of 2.8 years, 12 patients experienced at least one major coronary event (4 cardiac deaths, 5 myocardial infarctions and 3 revascularizations). Eight of the 17 patients with abnormal thallium uptake (47%) suffered a coronary event, compared to only 4 of the 43 patients (9%) with a normal thallium uptake (P < 0.001). The positive prognostic predictive value of thallium imaging was 47% and its negative predictive value was 91%. The probability of survival free of coronary events was significantly higher in patients with normal thallium uptake than in those with abnormal thallium uptake (crude risk ratio 7.6; P < 0.001) even after adjustment for several risk factors for cardiovascular disease (adjusted risk ratio 9.2; P < 0.005).
Conclusion: In dialysis patients, combined dipyridamole-exercise thallium imaging is an accurate method for detecting coronary stenosis and for predicting future coronary events.