Long-Term Survival Benefit from Revascularization Compared with Medical Therapy in Patients with or without Diabetes Undergoing Myocardial Perfusion Single Photon Emission Computed Tomography

Objective: To explore the long-term association of survival benefit from early revascularization with the magnitude of ischemia in patients with diabetes compared to those without diabetes using a large observational cohort of patients undergoing single photon emission computed tomography myocardial perfusion imaging (SPECT-MPI).

Research Design and Methods: Of 41,982 patients who underwent stress and rest SPECT-MPI from 1998 to 2017, 8,328 (19.8%) had diabetes. By using a propensity score, 8,046 patients with diabetes were matched to 8,046 patients without diabetes. Early revascularization was defined as occurring within 90 days after SPECT-MPI. Percent myocardial ischemia was assessed from the magnitude of reversible myocardial perfusion defect on SPECT-MPI. 

Results: Over a median 10.3-year follow-up, annualized mortality rate was higher for the patients with diabetes compared to those without diabetes (4.7 vs. 3.6%; p<0.001). There were significant interactions between early revascularization and percent myocardial ischemia in patients with and without diabetes (all interaction p-values <0.05). After adjusting for confounding variables, survival benefit from early revascularization was observed in patients with diabetes above a threshold of >8.6% ischemia and in patients without diabetes above a threshold of >12.1%. Patients with diabetes receiving insulin had higher mortality rate (6.2 vs. 4.1%; p<0.001), but there was no interaction between revascularization and insulin usage (interaction p-value=0.405). 

Conclusions: Patients with diabetes, especially those on insulin treatment, had higher mortality rate compared to patients without diabetes. Early revascularization was associated with a mortality benefit at a lower ischemic threshold in patients with diabetes compared to those without diabetes.