Value of Progression of Coronary Artery Calcification for Risk Prediction of Coronary and Cardiovascular Events: Result of the Heinz Nixdorf Recall (HNR) Study

Background —Computed tomography (CT) allows estimation of coronary artery calcium (CAC) progression. We evaluated several progression algorithms in our unselected, population-based cohort for risk prediction of coronary and cardiovascular (CV) events. Methods —In 3281 participants (45-74 years), free from CV disease until the 2 nd visit, risk factors and CTs at baseline (b) and after a mean of 5.1 years (5y) were measured. Hard coronary and cardiovascular events as well as total CV events including revascularization were recorded during a follow-up time of 7.8±2.2 years after the 2 nd CT. The added predictive value of ten CAC progression algorithms on top of risk factors including baseline CAC was evaluated using survival analysis, C-statistics, net reclassification improvement (NRI), and integrated discrimination index (IDI). A subgroup analysis of risk in CAC categories was performed. Results —We observed 85 (2.6%) hard coronary, 161 (4.9%) hard CV and 241 (7.3%) total CV events. Absolute CAC progression was higher with vs. without subsequent coronary events [median 115 (Q1-Q3 23-360) vs. 8 (0-83), p 5y and 5-year risk factors. An excellent prognosis was found for 921 participants with double zero CAC b =CAC 5y =0 [10-year coronary and hard/total CV risk: 1.4%, 2.0% and 2.8%], which was for participants with incident CAC 1.8%, 3.8% and 6.6%, respectively. When CAC b progressed from 1-399 to CAC 5y ≥400, coronary and total CV risk were nearly twofold compared to subjects, who remained below CAC 5y =400. Participants with CAC b ≥400 had high rates of hard coronary and hard/total CV events [10-year risk: 12.0%, 13.5% and 30.9%, respectively]. Conclusions —CAC progression is associated with coronary and CV event rates, but adds only weakly to risk prediction. What counts is the most recent CAC value and risk factor assessment. Therefore, a repeat scan more than five years apart may be of additional value, except when a double zero CT scan is present or when the subjects are already at high risk.