Abstract 2330: Relationship Between Coronary Calcification, Myocardial Ischemia, and Outcomes in Patients With Intermediate Likelihood of Coronary Artery Disease
Background - Although the value of coronary artery calcium (CAC) for atherosclerosis screening is gaining acceptance, its efficacy in predicting flow-limiting CAD remains controversial and its incremental prognostic value over myocardial perfusion is not well established.
Methods and Results - We evaluated 621 consecutive patients undergoing combined rest-stress Rubidium-82 PET perfusion imaging and CAC scanning on a hybrid PET-CT scanner. The frequency of abnormal scans among patients with CAC ≥400 was higher than that in patients with CAC 1–399 (53.3% vs 30.0%, p<0.001). Multivariate logistic regression analysis supported the concept of a CAC ≥400 threshold value governing this relationship (OR 2.74, p<0.001). However, the frequency of ischemia among patients with no CAC was 24.4%, and its absence only afforded a negative predictive value of 75.6%. Risk adjusted survival analysis demonstrated a stepwise increase in event rates with increasing CAC scores in patients with and without ischemia on PET. Among patients with normal PET, the annualized event rate in patients with CAC score=zero was lower than in those with a CAC ≥1,000 (2.4% vs 13.6%, respectively). Likewise, in patients with ischemia on PET the annualized event rate in those with CAC score=zero was lower than among patients with a CAC ≥1,000 (6.9% vs 19.4%).
Conclusions - Although increasing CAC scores are generally predictive of a higher likelihood of ischemia, its absence does not eliminate the possibility of flow-limiting CAD. Importantly, there is a stepwise increase in the risk of adverse events with increasing CAC scores in patients with and without ischemia on PET.