Background: While the Framingham Risk Score provides a reasonable estimation of risk in certain subgroups, the majority of MIs occur in individuals classified as low or moderate risk. Coronary Artery Calcium (CAC) testing provides an individualized measure of atherosclerotic burden that integrates an individual’s cumulative lifetime risk factor exposure that cannot be obtained from serum markers.
Methods and Results: We briefly summarize the existing evidence for the use of CAC scanning in primary prevention and performed a meta-analysis of the existing randomized controlled data investigating the impact of CAC screening on lifestyle modification, risk factors, and downstream testing. We identified four trials published between 2003 and 2011 with a total of 2,490 participants, >75% of whom came from the Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research (EISNER) trial. Three of the trials reported a non-significant increase in smoking cessation in the scan versus no-scan group with a pooled mean of 1.15 (95% CI 0.77 – 1.71). A significant reduction in SBP and LDL was noted in the EISNER trial, but the pooled estimates were 0.23mmHg (95% CI −2.25 – 2.71) and 0.23mg/dL (95% CI −5.96 – 6.42), respectively. Only the EISNER trial reported medication usage according to CAC score. They found a higher CAC score associated with an increased prescription of lipid lowering medications (p=<0.001) and a CAC=0 associated with fewer prescriptions for lipid lowering medications (p=0.02).
Conclusions: Our meta-analysis highlights the paucity of randomized evidence linking CAC scanning to improved intermediate and hard outcomes in primary prevention. Future trials are urgently needed to determine the impact of CAC screening on lifestyle modification, risk factor modification, and downstream testing.