Abstract 20574: Is Myocardial Perfusion Imaging Appropriate in All Patients with Excellent Functional Capacity?
Background: Functional capacity (FC) determined by the exercise stress test (EST) is an important predictor of all-cause mortality. A recent study suggested a limited role for myocardial perfusion imaging (MPI) in patients with excellent FC. We attempted to confirm these Results by examining the relationship between FC and incidence of abnormal MPI in patients without a prior history of coronary artery disease (CAD) who were referred for EST with MPI.
Methods: Retrospective analysis of 3,220 consecutive patients without prior CAD referred for EST with MPI from July 1, 2007 through March 31, 2009. Patients were divided into tertiles based on estimated metabolic equivalents (METs): tertile 1: <7 METs (n=1,078), tertile 2: 7–10 METs(n= 1,062), and tertile 3: >10 METs (n= 1,085). Abnormal MPI was defined as a summed stress score (SSS) >0 or left ventricular ejection fraction (LVEF) <50% to detect any abnormalities in this population without prior CAD.
Results: Among 3220 study patients (52% males), there were 321 abnormal MPI (154: SSS>0, 209: EF< 50% and 42 had SSS>0 and LVEF<50%). Incidence of abnormal MPI was inversely related to FC (tertile 1: 13.5%; tertile 2: 9.7% and tertile 3: 7.2% p < 0.001). Patients in tertile 3 were more likely younger, male and without diabetes and hypertension (p<0.001). On multivariable modeling, male gender, baseline ECG, exercise ST depression and FC were significant predictors of abnormal MPI (p<0.001, global chi square=243). Age was not a significant predictor in this model after inclusion of FC (p=0.27). Among the 1,085 patients in tertile 3, only 12 patients (1.1%) had SSS>0 without ST depression on ECG. In this group, coronary angiography was normal in 5 patients, showed obstructive CAD in 2 patients and was not performed in the others. High-risk scan (SSS>12) was present in only one patient who had a history of peripheral vascular disease.
Conclusions: The incidence of abnormal MPI is very low in patients exercising >10METS without ST depression or chest pain, confirming previously published results. These data suggest that EST without MPI is the most appropriate initial diagnostic test in patients without prior CAD who are likely to have an excellent FC.
- © 2010 by American Heart Association, Inc.