Abstract Body (Do not enter title and authors here): Background: Coronary artery calcium (CAC) is a strong predictor of coronary artery disease (CAD) risk, and CAC=0 is a highly favorable prognostic marker. Recently, the prognostic value of CAC has been proposed to extend to all-cause and non-coronary mortality. For example, CAC is a predictor of calcification in other vascular beds, and CAD is reported to impact immune surveillance and cancer risk.
Methods: We tested whether CAC can predict the risk of total mortality (TM), and we estimated whether cause-specific and non-coronary mortality distributions are impacted by CAC. We searched the Intermountain Health electronic medical records (eMR) database for patients (pts) at primary coronary risk who underwent positron emission tomography/computed tomography (PET/CT) stress testing and had a 5y follow-up. We compared unadjusted and age/sex-adjusted TM rates between CAC=0 and CAC>0 pts. We determined cause-specific mortality proportions for all CAC=0 pts and estimated these from a 1:10 random sample of CAC>0 pts by chart review. We examined proportions of 5y cause-specific deaths in CAC=0 pts and explored differences with CAC>0 patients.
Results: The eMR search identified 40,018 pts undergoing PET/CT who were at primary coronary risk. Mean age was 65.8 [11.9] y; 48.7% were female; 7967 (19.9%) had CAC=0 by CT; and 32,051 were CAC>0. There were 238 deaths (2.99%) in CAC=0 and 2834 (8.84%) in CAC>0 cohort, for a relative risk (RR) of 0.34 (p<0.001). In age and sex adjusted logistic regression, CAC>0 remained a highly significant risk factor (OR=2.04, p<0.0001; Table 1). Distributions of cause-specific deaths are shown in Table 2 by CAC category. CAC=0 predicted a very low proportion of CAD-related and total cardiovascular (CV) deaths. Most of the greater rate of TM in CAC>0 patients was estimated to be non-CV.
Conclusions:
In this large, integrated healthcare system experience, a zero CAC score predicted an excellent prognosis for TM, with CAC>0 being associated with a >2-fold greater TM risk than CAC=0. Further, CAC=0 was associated with a very low proportion of both CAD-related and all CV mortality. Most of CAC>0 TM was estimated to be non-CV. The implications of a zero CAC score may go beyond simply marking a low risk of CAD-related events to also being a marker of general vascular health and improved overall survival.