Increased prognostic value of combined myocardial perfusion imaging and exercise electrocardiography in patients with coronary artery disease

Background. Myocardial perfusion imaging (MPI) with technetium-99m-labeled sestamibi and exercise electrocardiography (EECG) are widely used for risk stratification of patients with known or suspected coronary artery disease (CAD). However, no large-scale studies have addressed the prognostic po,rer of the combined information from these diagnostic tools. Methods and Results. We studied 697 consecutive patients who underwent a 2- day Tc-99m sestamibi cardiac perfusion imaging protocol. The EECG was perfo rmed on a bicycle ergometer by symptom-limited exercise. Causes of death we re obtained from death certificates, Univariate survival analyses were perf ormed with a Kaplan-Meier estimate and a corresponding log-rank test. A mul tivariate Cox proportional hazards model was applied to test for potential predictor covariates obtained from hospital records. The predominant risk f actors of cardiac death were fixed perfusion defects (relative risk, 2.55; range, 1.43 to 4.55) and an impaired circulatory exercise response (relativ e risk, 3.26; range, 1.74 to 6.08), The major prognostic information of MPI was the ability to detect patients with a definitively low risk. Patients with impaired circulatory response to exercise test and fixed perfusion def ects were at a very high risk. Conclusion. The combined results of MPI and EECG provide substantial inform ation on the long-term risk of cardiac death in patients with suspected CAD .