Abstract 319: Relationship Between Coronary Artery Calcium Score and Myocardial Perfusion by Positron Emission Tomography Myocardial Perfusion Imaging
Background: The presence of coronary artery calcium (CAC) increases the likelihood of ischemia on SPECT myocardial perfusion imaging (MPI). We evaluated the relationship between CAC scores and myocardial ischemia in patients undergoing PET/CT MPI.
Methods: Data from 2,094 consecutive pts with no history of CAD who underwent PET/CT MPI and same-setting CACS were analyzed. The frequency of myocardial ischemia by Agatston score was calculated. Multivariable analysis controlling for age, gender, medical history, and CACS assessed the independent association of CAC score (CACS) and likelihood of an ischemic scan.
Results: Of the 312 patients with an ischemic PET MPI, the Agatston CACS was 0 in 9%, 1 to 99 in 16%, 100 to 399 in 23%, 400 to 999 in 26%, and ≥1000 in 26%. Of the 1,782 patients with non-ischemic PET MPI, the CACS was 0 in 33%, 1 to 99 in 32%, 100 to 399 in 17%, 400 to 999 in 11%, and ≥1000 in 7%. The frequency of ischemic PET MPI was 4% for CACS=0, 8% for CACS 1 to 99, 19% for CACS 100 to 399, 30% for CACS 400 to 999, and 41% with CACS ≥ 1000 (p for trend <0.001). The median summed stress score was 8 (IQR 5,13) in the ischemic group and 0 (0, 0) in the non-ischemic group. Multivariable analysis showed that the CACS adds incremental predictive value for the presence of ischemia.
Conclusions: Increasing CACS is associated with a greater likelihood of ischemia by PET MPI. The likelihood of myocardial ischemia increases significantly when the CACS is > 99. Nine percent of patients with ischemic PET MPI had a CACS of 0, thus a CACS of 0 does not rule out the possibility of functionally significant CAD. The CACS adds incrementally, beyond clinical predictors of CAD, to the likelihood of myocardial ischemia on PET/CT MPI.