The risk for sudden cardiac death (SCD) climbs steadily in tandem with coronary artery calcium (CAC) burden, independent of more conventional risk factors, in primary-prevention patients considered low- to intermediate-risk, researchers say.
The findings, based on a large cohort study, strengthen the case for initial CAC imaging as a gatekeeper to further testing in such patients who have mostly subclinical atherosclerotic cardiovascular disease (ASCVD), they conclude.
The CAC scan is "evolving into a primary-prevention screening test, not only for initiating statin therapy, but now as a screening modality for risk stratifying someone for sudden cardiac arrest," Alexander C. Razavi, MD, MPH, PhD, Johns Hopkins University School of Medicine, Baltimore, told theheart.org | Medscape Cardiology.
"Our data reinforce this and give some quantitative measures of when we should start to consider that."
A CAC score of 100 to 399 in this "primarily asymptomatic," predominantly White and male cohort elevated the risk for SCD over an average of 10.6 years by a factor of 2.8, compared with a score of 0. The risk went up four times with CAC scores of 400 to 999, and almost five times with scores above 1000.
The risk association was independent of age and sex, but also diabetes, smoking, hypertension, dyslipidemia, and family history of heart disease.
That and other findings, Razavi said, suggest CAC scores in low- to intermediate-risk patients like those studied may sharpen SCD risk-stratification beyond what is possible using traditional risk factors.
Razavi is lead author on the study's March 21 publication in JACC Cardiovascular Imaging, and is slated to present the results April 2 during the American College of Cardiology (ACC) 2022 Scientific Session, to be held virtually and in-person in Washington, DC.
The study's 66,636 primary-prevention patients, part of the Coronary Artery Calcium Consortium observational cohort, were without known coronary disease at enrolment, from 1991 to 2010, at four major American centers. They had been referred to CAC imaging because of the presence of at least one ASCVD risk factor, such as dyslipidemia, family history of premature heart disease, hypertension, or diabetes, the researchers note.
They observed 211 SCD events, for a rate of about 0.3%, over a median of 10.6 years. The adjusted stepwise higher risk (SHR) for an SCD event went up continuously with CAC scores (P for trend < .001). The SHR values, compared with a CAC score of 0, were:
1.3 (95% CI, 0.7 - 2.4) for a CAC score score of 1 to 99
2.8 (95% CI, 1.6 - 5.0) for a CAC score of 100 to 399
4.0 (95% CI, 2.2 - 7.3) for a CAC score of 400 to 999
4.9 (95% CI, 2.6 - 9.9) for a CAC score above 1000.
The magnitude of the CAC score's association with SCD risk in the study was "surprising," Razavi said. The CAC score, starting at about 100, seems "more strongly associated with a sudden cardiac arrest" than more familiar SCD risk predictors, such as prolonged heart-rate-corrected QT (QTc) interval or QRS duration.
Razavi reported no conflicts. Disclosures for the other authors are in the report.
American College of Cardiology 2022 Scientific Session. Abstract 1032-07.
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