Prognostic significance of previous myocardial infarction and previous revascularization in patients undergoing SPECT MPI

Background: Accurate risk stratification in patients with known coronary artery disease (CAD) is critical for patient management. Prior myocardial infarction (MI) or revascularization without MI are often equated as known CAD. We compared the prognostic significance of prior MI and previous revascularization in patients undergoing single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). Methods: Consecutive patients undergoing SPECT MPI at Cedars-Sinai Medical Center between 1992 and 2012 were included. Medical history, including history of MI or revascularization, was collected prospectively. Association with all-cause mortality was assessed with multivariable Cox analysis, adjusted for patient demographics, medical history, medications, and SPECT MPI results. Results: In total, 50,121 patients were identified including 7428 (14.8%) with a history of previous MI and 3608 (7.2%) with a history of revascularization without prior MI. During a median follow-up of 8.0 years, 19,696 (39.3%) patients died including 4467 (60.1%) with a history of MI and 1880 (52.1%) with a history of revascularization. Prior MI (adjusted HR 1.12, p=0.001) and prior revascularization without MI (adjusted HR 1.15, p<0.001) were independently associated with increased all-cause mortality. Previous MI (adjusted HR 1.27, p<0.001) and previous revascularization without MI (adjusted HR 1.21, p<0.001) were significantly associated with increased all-cause mortality only in patients without ischemia. Conclusions: In this large cohort of patients undergoing SPECT MPI, previous MI and previous revascularization without MI were independent predictors of all-cause mortality, with no significant difference in associated risk. History of CAD may be particularly important for risk stratification in patients without ischemia.