Abstract
Introduction
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.
Purpose
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 patients with diabetes undergoing both tests.
Methods
Consecutive patients with diabetes who underwent clinically indicated CCTA and SPECT myocardial imaging for suspected coronary artery disease at a tertiary care center were retrospectively identified from medical records. Stenosis severity and segment involvement score (SIS) were determined from CCTA, and presence of ischemia was determined from SPECT. Patients were followed from date of imaging 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 778 patients were included (mean age 60.6±14.4 years, 55% males). Obstructive stenosis (left main ≥50%, all other coronary segments ≥70%) and ischemia were found in 15% and 16% of patients respectively. After a median follow-up of 31 months, 87 (11%) patients experienced a MACE. In multivariable Cox regression models, SIS significantly predicted outcomes in models including obstructive stenosis and ischemia (HR 1.17, 95% CI 1.10 - 1.24, p<0.001; 1.16, 95% CI 1.10 - 1.23, p<0.001). The addition of SIS also significantly improved discrimination (Harrel's C 0.75, p=0.006; 0.76, p=0.006 in models with CCTA obstructive stenosis and SPECT ischemia respectively). Results were consistent using subgroups of summed scores by composition of plaque (calcified vs non-calcified) and alternate definitions of obstructive stenosis.
Conclusion
Our results suggest that in high-risk patients with diabetes and suspected coronary disease, SIS has incremental prognostic value over ischemia by SPECT or stenosis by CCTA in predicting incident cardiovascular outcomes.
FUNDunding Acknowledgement
Type of funding sources: None.
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