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22-11-2016 | Cardiology | News | Article

Coronary artery calcification improves atherosclerotic CVD risk prediction in low-risk women

medwireNews: Coronary artery calcification (CAC) is associated with increased risk for atherosclerotic cardiovascular disease (ASCVD) and improved prognostic accuracy among low-risk women, study findings published in JAMA suggest.

“These results further strengthen the current evidence by showing that CAC has the potential to modestly improve risk discrimination and to further risk stratify asymptomatic individuals categorized as having low ASCVD risk by the recent guidelines,” write Maryam Kavousi (Erasmus University Medical Center, Rotterdam, the Netherlands) and colleagues.

In a meta-analysis of data from 6739 women included in five large population-based cohort studies, the researchers found that CAC was present in 36.1% of 2435 women classified as having low (<7.5%) 10-year risk for ASCVD by the 2013 American College of Cardiology and American Heart Association (ACC/AHA) CVD prevention guidelines.

ASCVD – a composite of nonfatal myocardial infarction, death due to coronary heart disease, and stroke – occurred at an incidence rate of 4.33 per 1000 person–years in women with CAC, compared with 1.41 per 1000 person–years in those without CAC, representing an incidence rate difference of 2.92.

After adjustments for traditional cardiovascular risk factors (including age, ethnicity, cholesterol levels, smoking status, blood pressure, and diabetes), women with CAC were about twice as likely to experience ASCVD as those without CAC.

The authors explain that based on current clinical practice guidelines, “a large group of women are categorized as having low or intermediate CVD risk and would therefore not typically qualify for pharmacologic management of standard risk factors.”

They add that the “[b]urden of calcification of the coronary arteries is viewed as an integrated measure reflecting the cumulative exposure to risk factors over the lifetime,” which could “improve cardiovascular risk prediction and stratification above the current risk-scoring algorithms.”

The addition of CAC to a model accounting for traditional CVD risk factors improved ASCVD prediction in all five cohorts studied, as demonstrated by an increase in the overall C statistic from 0.73 to 0.77.

Although the addition of CAC to risk prediction algorithms was associated with “a small improvement in discrimination,” the overall incidence rate of 4.33 per 1000 person–years for CAC presence was “still below the typical treatment threshold (7.5% ASCVD risk) recommended by the [ACC/AHA] guidelines,” note the authors.

However, “CAC testing has been shown to improve therapeutic compliance not only in terms of adherence to medication but also with lifestyle changes including diet and exercise,” they add.

The researchers conclude that “[f]urther research is needed to assess the clinical utility and cost-effectiveness” of the additional prognostic accuracy provided by CAC.

By Claire Barnard

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