January 29, 2016
2 min read

Progression of CAC corresponds to heightened risk for AF

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Progression of coronary artery calcium during an average of 5 to 6 years is associated with increased risk for atrial fibrillation, according to new data from the Multi-Ethnic Study of Atherosclerosis.

Prior research had shown that a high coronary artery calcium (CAC) score from a single time point is associated with increased risk for AF, but little was known whether the same was true for CAC progression measured during multiple time points, according to the study background.

Researchers analyzed 5,612 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) study (mean age, 62 years; 52% women; 39% white) with no clinical CVD at baseline.

They used phantom-adjusted Agatston scores from baseline and follow-up CAC measurements to calculate change in CAC each year, stratified into quartiles: up to 0 U/year; 1 U/year to 100 U/year; 101 U/year to 300 U/year; and greater than 300 U/year.

The outcome of interest was onset of AF, verified by hospital discharge records and Medicare claims data through December 2010. Median follow up was 5.6 years (interquartile range, 5.1-6.8).

Wesley T. O’Neal, MD, MPH

Wesley T. O’Neal

During the study period, Wesley T. O’Neal, MD, MPH, and colleagues verified 203 (3.6%) new cases of AF.

AF risk elevated

Compared with CAC progression up to 0 U/year, CAC progression greater than 0 U/year was associated with elevated risk for AF (HR = 1.55; 95% CI, 1.1-2.19), O’Neal, from the department of internal medicine at Wake Forest School of Medicine, Winston-Salem, North Carolina, and colleagues found.

The greater the CAC progression, the greater the risk for AF (HR for CAC progression 1-100 U/year = 1.47; 95% CI, 1.03-2.09; HR for CAC progression 101-300 U/year = 1.92; 95% CI, 1.15-3.2; HR for CAC progression > 300 U/year = 3.23; 95% CI, 1.48-7.05), they found.

The association between CAC progression and AF was stronger in those aged 60 years or younger (HR = 3.53; 95% CI, 1.29-9.69) than in those aged at least 61 years (HR = 1.42; 95% CI, 0.99-2.04; P for interaction = .037), according to the researchers.

“In aggregate, the results of our [two] analyses in MESA suggest that the relationship between CAC and AF depends on the baseline level of CAC detected and the extent of CAC progression over time,” O’Neal and colleagues wrote. “Additionally, our data provide evidence that CAC progression is an important risk factor for AF development in persons without CAC from a single measurement. These persons may be deemed low-risk by single CAC measurements and subsequently reclassified as a population more likely to develop AF if CAC progression occurs.”

Jonathan P. Piccini, MD

Jonathan P. Piccini,

Not ready for prime time?

In a related editorial, Sean D. Pokorney, MD, MBA, and Jonathan P. Piccini, MD, MHS, FACC, FAHA, FHRS, both from the electrophysiology section, Duke Center for Atrial Fibrillation, Duke University Medical Center, Duke Clinical Research Institute, wrote that “[CT] scans are not ready for widespread clinical use to determine CAC progression as a means of classifying the risk of incident AF” because the study relied in detection of AF from reports by patients and inpatient Medicare claims data, and did not adjust for risk factors such as left atrial size, HF and sleep apnea, noting that other research suggests the link between CAC and AF might be explained by atrial ischemia.

Nonetheless, they wrote, use of CAC scores “should be helpful in developing studies to test strategies to prevent AF in patients with vascular disease.” – by Erik Swain

Disclosure: One researcher reports consulting for and receiving institutional research funding from Biosense Webster. The other researchers report no relevant financial disclosures. Pokorney reports financial ties with AstraZeneca, Boston Scientific, Gilead Sciences and Janssen Pharmaceuticals. Piccini reports financial ties with ARCA Biopharma, AHRQ, Boston Scientific, Gilead Sciences, GlaxoSmithKline, Laguna Pharmaceuticals, Medtronic, Pfizer/Bristol-Myers Squibb, ResMed, Spectranetics and St. Jude Medical.