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Impact of Statins on CV Outcomes After CAC Scoring
Study Questions:
Does the coronary artery calcium (CAC) score identify persons most likely to have a reduction in atherosclerotic cardiovascular disease (ASCVD) events with statin treatment?
Methods:
The authors identified consecutive subjects without pre-existing ASCVD or malignancy who underwent CAC scoring from 2002 to 2009 at Walter Reed Army Medical Center. CAC score was obtained at the discretion of the ordering provider. The primary outcome was first major adverse cardiac event (MACE), a composite of acute myocardial infarction, stroke, and CV death. The effect of statin therapy with a threshold of 50% compliance during follow-up before an outcome of interest was analyzed stratified by CAC presence and severity, after adjusting for baseline comorbidities with inverse probability of treatment weights based on propensity scores.
Results:
A total of 13,644 patients (mean age 50 [8] years; 71% men) were followed for a median of 9.4 years. About 50% were treated with a statin with 50% within 6 months prior to the CAC score. Patients on statins (80% low- or medium-intensity for a mean of 5.5 years) were older, male, and had a greater number of risk factors. Sixty-nine percent had no detectable CAC. Comparing patients with and without statin exposure, statin therapy was associated with reduced risk of MACE in patients with CAC (adjusted subhazard ratio, 0.76; 95% confidence interval [CI], 0.60-0.95; p = 0.015), but not in patients without CAC (adjusted subhazard ratio, 1.00; 95% CI, 0.79-1.27; p = 0.99). The effect of statin use on MACE was significantly related to the severity of CAC (p < 0.0001 for interaction), with the number needed to treat to prevent one initial MACE outcome over 10 years ranging from 100 (CAC 1-100) to 12 (CAC >100). Statin intensity was an independent predictor of improved MACE-free survival. Patients with no CAC and otherwise high ASCVD (>20%) had a 74% reduction in hazard of MACE with statin therapy p < 0.01), but there was no benefit of statins in those with no CAC and low or intermediate baseline risk. Patients with a CAC >100 had a 64-71% reduction in MACE even with low (<5%) or intermediate risk (5-20%), p < 0.0001 for each.
Conclusions:
In a large-scale cohort without baseline ASCVD, the presence and severity of CAC identified patients most likely to benefit from statins for the primary prevention of CVDs.
Perspective:
This study lends strong support to the 2018 American College of Cardiology/American Heart Association blood cholesterol guidelines recommending a CAC score to assist in the decision to use statins in the low- to intermediate-risk cohort. Importantly, the CAC score was predictive in this young ‘real-world’ cohort. Also importantly, the absence of calcium should not infer that statins are not warranted in high-risk subjects.
Keywords: Atherosclerosis, Cholesterol, Comorbidity, Diagnostic Imaging, Myocardial Infarction, Plaque, Atherosclerotic, Primary Prevention, Risk Factors, Stroke, Vascular Diseases
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