Silent ischemia: Discordance between symptoms and disease progression in diabetics with spect myocardial perfusion imaging

Abstract

Background: Patients with diabetes have a high burden of coronary artery disease (CAD) yet may have atypical or no symptoms. We evaluated the progression of CAD in diabetics (DM) and non-diabetics (Non-DM) who underwent serial Myocardial Perfusion Imaging (MPI). Methods: Our single center database of Tc-99m rest/stress MPI studies in patients with known or suspected CAD was evaluated for patients with initially normal MPI who underwent clinically indicated repeat imaging without intervening infarction or revascularization (DM =187, Non-DM=488). Patients were categorized as MPI remaining normal or converting to abnormal (fixed or reversible). Results: Age, gender, history of CAD or revascularization and percent excluded did not differ between groups. Recurrent symptoms of chest pain were the indication for retesting in 77% of patients. More diabetics were sent for re-testing compared to non-diabetics (14.5% vs. 8.7%, p<0.001). Over two years, diabetics were more likely to convert to abnormal than non-diabetics (32.1% vs. 21.2%, p=0.007). Overall time to repeat testing was not statistically different between diabetics and non-diabetics (796.1 vs. 789.0 days, p=0.87). Among patients converting to abnormal, diabetics had a significantly longer time to repeat symptom-guided testing (840.2 vs. 666.0 days, p<0.02). Repeat MPI Diabetic Status Inter-test Interval (days) S.D. P Normal Diabetic 747.7 471.6 n.s. Non-Diabetic 809.4 477.3 Abnormal Diabetic 840.2 481.3 0.02 Non-Diabetic 666.0 424.8 Conclusion: Diabetics are at greater risk for progression of CAD than non-diabetics. The delay in clinically indicated repeat testing in diabetics converting to abnormal suggests that symptom-guided surveillance may not promptly identify progressive CAD in diabetics.