According to a new study published in the Journal of American College of Cardiology, patients with higher coronary artery calcium (CAC) scores were more likely to achieve benefit from statins in the primary prevention of cardiovascular disease.
Positive CAC associated with benefit, Higher CAC associated with more benefit
The observational, retrospective study looked at data from 13,644 patients -without pre-existing evidence of atherosclerotic coronary artery disease (ASCVD)- who underwent CAC scoring between 2002 and 2009 at Walter Reed Army Medical Center (Washington, DC). The patients were followed for a median of 9.4 years for the occurrence of the primary outcome of the first major adverse cardiac event (MACE) defined as a composite of acute myocardial infarction, stroke, and cardiovascular death.
“To our knowledge, our study is the largest to evaluate the effectiveness of statin treatment in patients with CAC, and the only study to directly compare the direct benefit of statin use between CAC groups.” – Mitchell et al.
It was found that statins were associated with significant reduction of MACE risk in patients with CAC score >0 (adjusted sub-hazard ratio 0.76; 95% CI 0.60 to 0.95; P =0.015). While in patients with CAC score = 0, statins were not associated with decreased risk of MACE (adjusted sub-hazard ratio 1.00; 95% CI 0.79 to 1.27; P = 0.99). Additionally, increased CAC score was associated with increased benefit from statins. In patients with a CAC score of 1-100, the number needed to treat (NNT) was 100 (P = 0.095). While in patients with CAC score of more than 100, NNT was 12 (P = 0.0001).
CAC of 100 as a cutoff
The authors claim that their study “may be the first to show the ability of a screening test to potentially tailor a statin treatment strategy.” According to them, CAC is a good screening measure to assess the potential benefit from statin in the primary prevention of cardiovascular disease as it can measure the level of atherosclerosis in the coronary arteries directly. Also, the authors recommend using a CAC score of 100 as a cutoff for selecting patients who are more likely to benefit from statins.
“It is critical that the new guidelines clearly articulate the primary role of the CAC test in the current environment to clarify the uncertainty around risk estimates, and this approach does not equate with screening. In fact, rather than screening additional statin candidates, CAC testing’s true value via the power of zero lies in distinguishing who may or may not benefit from pharmacological preventive therapies.”- Dr. Khurram Nasir, MD, MPH, MSc
In the accompanying editorial, Dr. Khurram Nasir (School of Medicine, Yale University) commented, “It is critical that the new guidelines clearly articulate the primary role of the CAC test in the current environment to clarify the uncertainty around risk estimates, and this approach does not equate with screening.” In fact, rather than screening additional statin candidates, “CAC testing’s true value via the power of zero lies in distinguishing who may or may not benefit from pharmacological preventive therapies,” he added.
Recommendations from the most recent guidelines
The most recent AHA guidelines recommend initiating risk discussion -about statins use for primary prevention- with patients aged 40-75 years without diabetes mellitus with LDL-C level between 70 and 190 mg/dl and their 10-year ASCVD risk is between 7.5% and 20%. If the risk decision is uncertain, the guidelines recommend using the CAC scoring to guide the decisions as the following:
- CAC = 0: no statin unless cigarette smoking or history of premature CVD is present
- CAC = 1-99: statins are preferred especially if the patient is older than 55 years old.
- CAC ≥ 100: statins should be initiated.
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