Added Prognostic Value Of Plaque Burden To Computed Tomography Angiography And Myocardial Perfusion Imaging

Purpose: Cardiac computed tomographic angiography (CCTA) - derived measures of coronary artery disease (CAD) burden such as segment involvement score (SIS), which quantifies the number of segments with plaque, have been shown to independently predict incident cardiovascular events. We aimed to compare the added prognostic value of plaque burden to CCTA anatomic assessment and single photon emission computed tomography (SPECT) physiologic assessment in a high-risk cohort undergoing both tests.Methods: Consecutive patients who underwent clinically indicated CCTA and SPECT myocardial imaging for suspected CAD at a tertiary care cardiology practice were included. Stenosis severity and SIS were determined from CCTA, and presence of ischemia was determined from SPECT. Patients were followed for major adverse cardiovascular events (MACE, inclusive of all-cause death, non-fatal myocardial infarction, and percutaneous coronary intervention or coronary artery bypass grafting 90-days after imaging test.)Results: A total of 956 patients were included. Mean age was 61.1 ± 14.2 years, 54% were men, 89% had hypertension, 81% had diabetes, 84% had dyslipidemia and 56% had recorded chest pain. Obstructive stenosis (left main ≥ 50%, all other coronary segments ≥ 70%) and ischemia were observed in similar number of patients (14%). After a median follow-up of 31 months, 102 patients (11%, 29.2 events per 1000 person-year) experienced a MACE. In multivariable Cox regression models, SIS significantly predicted outcomes and improved risk discrimination in models with CCTA obstructive stenosis (HR 1.15 95% CI 1.09 - 1.21 p= Conclusion: Our results suggest that in high-risk patients with suspected CAD, plaque burden adds incremental prognostic value over established measures in predicting incident cardiovascular outcomes.