Abstract 3639: Referral Patterns For Stress Myocardial Perfusion Imaging by Medical Specialty: Correlation with ACC/AHA Guidelines
Introduction: ACC/AHA guidelines for management of chronic stable angina recommend initial exercise treadmill testing (ETT) in patients presenting for an outpatient evaluation of chest pain and an intermediate risk of coronary artery disease (CAD).
Methods: We completed a retrospective chart review of 753 outpatients referred consecutively for stress myocardial perfusion imaging (MPI) at a large tertiary care hospital. The referring physician specialty, demographics, and pretest probability were obtained. Patients with prior history of CAD were excluded and 482 patients were subsequently analyzed.
Results: There was no difference between the groups with respect to gender, BMI, baseline lipids, diabetes, and smoking status except hypertension was more prevalent among cardiology (C) referrals (64% vs 39% family practice (FP) and 48% Internal Medicine (IM); p=0.021). There was no difference between groups with respect to exercise time, maximum MET level achieved, baseline EF, and quality of chest pain which was typical in the majority of patients. Thirty nine percent of patients were of intermediate risk for CAD, an appropriate referral group for stress testing. All patients had normal baseline ECGs. Positive stress ECGs were seen in 9% while positive MPI results were seen in 4%. Two hundred and ninety six patients (61%) were classified as low or high pretest probability for CAD making stress imaging inappropriate, which included 64% of C, 62% FP and 60% of IM referrals.
Conclusions: The use of outpatient MPI has a significant impact on medical costs which may be reduced by appropriate risk stratification and by following ACC/AHA guidelines. Based on current guidelines, approximately 61% of outpatient referrals for stress MPI by IM, FP, or C were inappropriate based on pretest likelihood of disease. All of the patients referred for stress MPI had a normal ECG, making ETT without MPI, the more appropriate initial test. Medical specialty did not impact referral patterns.