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CAC absence with common risk factors may confer low CVD odds
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Patients with no coronary artery calcium had a low 10-year risk for atherosclerotic CVD, even in the presence of traditional risk factors, according to a letter published in JACC: Cardiovascular Imaging.
“This information really informs the discussion that clinicians should have with their patients about whether or not to start statins or how aggressive to be with the preventive therapies in people who have not had [MIs] or strokes in the past,” Parag H. Joshi, MD, MHS, assistant professor of internal medicine at University of Texas Southwestern Medical Center in Dallas and a Cardiology Today Next Gen Innovator, said in an interview.
Researchers analyzed data from 3,923 participants (mean age, 58 years; 62% women) from the MESA study. Participants were free from atherosclerotic CVD and had baseline CAC between 0 and 10, where scores between 1 and 10 had a much higher risk than a score of 0.
“Other markers of risk like [C-reactive protein], which is an inflammatory marker, family history, which we know is somewhat helpful, and other tests don’t really reassure us when they’re normal, but [CAC], when it’s completely absent, can provide some reassurance,” Joshi told Cardiology Today.
The 2013 American College of Cardiology/American Heart Association atherosclerotic CVD risk estimator was used to categorize risk and examine events.
Those without CAC were more often younger, women, had lower prevalence of hypertension and less prevalence of a family history of CHD.
During a median of 10.3 years, 123 atherosclerotic CVD events occurred, of which 98 events involved patients with a CAC score of 0. Events included 41 MIs, 64 incident strokes and 18 CHD deaths. The occurrence of each event did not differ in participants with a CAC score of 0 and those with scores of 1 to 10. The event rates were 3.2 per 1,000 person-years in the overall cohort, 2.9 per 1,000 person-years in those with a CAC score of 0, and 5.4 per 1,000 person-years in those with a CAC score between 1 and 10.
Participants with a CAC score between 1 and 10 were twice as likely to develop atherosclerotic CVD compared with participants whose CAC score was 0 (HR = 1.86; 95% CI, 1.16-2.89).
The 10-year events did not exceed 7.5% in participants with no CAC but risks such as older age, diabetes and smoking.
The event rate for participants with a CAC score of 0 and an atherosclerotic CVD risk between 1% and 15% did not exceed 4.4 in 1,000 person-years, or 4.4% 10-year risk. Participants without CAC but an atherosclerotic CVD risk greater than 15% had an event rate up to 7.3 in 1,000 person-years, which is less than the 7.5% threshold recommended by the 2013 cholesterol treatment guidelines.
Multivariable models showed that the best predictors of atherosclerotic CVD were hypertension (HR = 2; 95% CI, 1.3-3.3), smoking (HR = 3; 95% CI, 1.8-5.1) and age (HR = 1.5; 95% CI, 1.2-1.9) in participants without CAC. For participants with CAC between 1 and 10, hypertension was the best predictor (HR = 9.9; 95% CI, 2.7-36.2), followed by age and smoking.
“When CAC is absent, we should still focus on [BP], smoking and healthy lifestyle choices,” Joshi said. “Given the best data that we have now, there is a lot of support for using [CAC scoring] in patients who are on the fence when you have that risk discussion about whether or not they should be on a statin to reduce their risk of [MI] and stroke, especially if they’ve never had one before.” – by Darlene Dobkowski
For more information:
Parag H. Joshi, MD, MHS, can be reached at parag.joshi@utsouthwestern.edu.
Disclosures: Joshi reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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