Abstract 1353: Short-term Referral Rates to Catheterization After Noninvasive Cardiac Imaging: Results From the Study of Myocardial Perfusion and Coronary Anatomy Imaging Roles in CAD (SPARC) Trial 90 Day Follow-up
Background: Post-cardiac imaging referral to invasive catheterization (CATH) is a primary measure of resource utilization and a major driver of cost.
Methods: We compared 90 day CATH between SPECT, PET, and 64 slice coronary CT angiography (CCTA) in 1,703 pts without prior CAD and intermediate high CAD likelihood recruited to SPARC, a prospective 41 site registry assessing post-cardiac imaging outcomes. Test results were categorized as normal (normal MPI, normal or nonobstructive CCTA), mildly abnormal (abnormal MPI with mild or no ischemia, obstructive CCTA without prox LAD, left main or 3VD) or significantly abnormal (>10% MPI ischemia, obstructive CCTA with prox LAD, left main or 3VD). The association between test result and CATH referral was assessed using logistic regression with adjustment for patient characteristics.
Results: The study was abnormal in 32% CCTA, 38% PET, and 22% SPECT (p<0.001). Overall, 160 CATH occurred, and differed by test: CCTA 15.2%, PET 12.1%, SPECT 4.2%; p<0.001. After adjusting for stress ECG, rest ECG, DM, HTN, dyspnea, angina, FMHx, sex, age, BMI, the test used significantly predicted CATH, with an interaction between modality and test result [both p<0.0001; Figure⇓ for predicted CATH rates]. Compared with SPECT, CATH was 11.8 times more likely after CCTA and 2.0 times as likely after PET.
Conclusions: In this prospective multicenter registry, CATH rates were similar after normal/non-obstructive results, but after both milder and more severely abnormal test results, CCTA was more likely to result in CATH than SPECT or PET. Whether this reflects excess CATH after CCTA or underutilization of CATH after MPI requires further investigation.