Value of simultaneous functional assessment in association with acute rest perfusion imaging for predicting short- and long-term outcomes in emergency department patients with chest pain

Background. Rest tomographic myocardial perfusion imaging (MPI) has significant utility for clinical decision making in emergency department chest pain patients. The role of functional data, commonly acquired with perfusion, has not been systematically evaluated. Methods and Results. Low- to moderate-risk patients undergoing rest MPI for risk stratification were included. The patients’ MPI findings were classified as normal (normal perfusion or function), abnormal (perfusion defect with abnormal regional function), or discordant (perfusion defect with normal regional function). Ejection fraction was determined from the gated MPI studies. Events based on perfusion classifications and ejection fraction were evaluated. A total of 2,826 consecutive patients (abnormal MPI results in 40%, normal in 32%, and discordant in 27%) were studied. Outcomes were similar for those with normal MPI results versus those with discordant MPI results (myocardial infarction [MI] based on troponin I [TnI], 3.5% vs 4.0%; MI based on creatine kinase-MB, 1.5% vs 1.7%; revascularization, 5.2% vs 5.5%; and MI/revascularization based on TnI, 7.9% vs 8.1%) (P=not significant for all). Both groups had significantly fewer events (P<.001 for all) when compared with patients with abnormal MPI studies (MI based on TnI, 15%; MI based on creatine kinase-MB, 10%; revascularization, 17%; MI based on TnI or revascularization, 24%). The mortality rate was not different among the 3 groups. Multivariate analysis showed that mild/moderate and severe systolic dysfunction were independent predictors of 30-day and 1-year mortality rates (P=.001). Conclusions. The concurrent evaluation of perfusion and function (regional and global) with MPI provides significant risk/outcome predictive power.