Variations in the referral patterns to pharmacologic and exercise myocardial perfusion imaging

Abstract

Background: Myocardial perfusion imaging (MPI) is commonly utilized for the non-invasive evaluation of patients with suspected coronary artery disease (CAD). It is either performed with exercise or pharmacologic stress. The objective of this study is to compare the referral patterns and diagnostic findings in patients referred for pharmacologic vs exercise MPI. Methods and Results: This was a prospective study of 429 consecutive patients who were referred for MPI at the American University of Beirut Medical Center (23% had pharmacologic stress with dipyridamole and 77% had exercise stress testing). Patients referred to pharmacologic stress were older, had a higher percentage of women, and a higher prevalence of diabetes and hypertension. There were more abnormal scans in the pharmacologic stress group (38% vs 20%, P < 0.001), as well as a higher prevalence of ischemia (21% vs 13%, P < 0.001) and impaired left ventricular function with an ejection fraction < 50% (19% vs 7.9%, P < 0.001). The significant predictors for referral to pharmacologic stress by multivariable logistic regression analysis were older age (OR = 2.01 (1.57–2.57), P < 0.001) and diabetes (OR = 2.04 (1.19–3.49), P = 0.009). Conclusion: Patients referred for pharmacologic stress MPI are at a higher risk than those referred for exercise stress MPI with more CAD risk factors, older age, and a higher prevalence of abnormal MPI findings.