Coronary artery calcification (CAC) progression was independently associated with outcomes of cardiovascular disease (CVD), but the relationship was not significant after factoring follow-up CAC, according to data published in JACC: Cardiovascular Imaging.
Nina B. Radford, MD, of the Cooper Clinic in Dallas, Texas, and colleagues conducted an observational study of 5933 patients who were free of CVD. Their goal was to determine the relative contributions of baseline CAC scanning, follow-up CAC, and CAC progression on incident CVD.
The patients underwent a CAC scan and subsequent CVD event assessment. The primary outcome of the study was total CVD events, which included CVD death, non-fatal myocardial infarction (MI), non-fatal atherosclerotic stroke, coronary artery bypass surgery (CABG), and percutaneous coronary intervention.
The secondary outcomes included hard CVD events (CVD death, non-fatal MI, non-fatal atherosclerotic stroke), total coronary heart disease (CHD) events (non-fatal MI, CABG, percutaneous transluminal coronary angiography or stent or CHD death), and hard CHD (non-fatal MI or CHD death) events.
“Our results demonstrate that while CAC progression may carry some prognostic information, this information is largely encompassed by the follow-up CAC score,” they wrote.
“This finding has important implications in that it simplifies the clinical interpretation of serial CAC scores for subsequent CVD risk by eliminating the need for the clinician to apply one or more complicated progression calculation methodologies to follow up CAC scores and instead allows the clinician to focus on the risk associated with the absolute score alone.”
At baseline, CAC was detected in 2870 individuals (48%). The average time between scans was 3.5 ± 2.0 years, and after the second scan, 161 individuals experienced a CVD event within the 7.3-year follow-up period.
In the model that included baseline CAC, CAC progression by square root method was significantly associated with total CVD events (hazard ratio [HR]: 1.14; 95% confidence interval [CI]: 1.01-1.30 per interquartile range; P=.042). However, the contribution of CAC progression was small relative to the baseline CAC (chi square 4.16 vs 65.92).
Importantly, CAC progression was not associated with total CVD events in the model including follow-up CAC instead of baseline CAC (HR: 1.05; 95% CI: 0.92-1.21 per interquartile range; P=.475). In addition, the model that included follow-up CAC alone performed as well as the model that included baseline CAC and CAC follow-up (HR: 1.36; 95% CI: 1.08-1.71 and HR: 1.42; 95% CI: 1.11-1.81, respectively).
“The importance of this finding is that it simplifies the debate regarding the optimal method of quantifying CAC progression for clinical purposes,” the authors concluded. “Ultimately, the follow-up CAC score alone can be used for risk assessment decisions without specific focus on the progression rate.”
Disclosures: The study was funded by the National Space Biomedical Research Institute through NASA NCC 9-58.
Radford NB, DeFina LF, Barlow CE, et al. Progression of coronary artery calcification score and risk of incident cardiovascular disease. JACC Cardiovasc Imag. 2016. doi: 10.1016/j.jcmg.2016.03.010.