A Zero Coronary Artery Calcification Score Does Not Mean Zero Risk

Coronary artery calcification (CAC) scoring is useful in deciding which patients with low or borderline atherosclerotic cardiovascular disease (ASCVD) risk require more aggressive risk factor treatment. A CAC score of zero portends low risk, but a zero score, does not equal zero risk. Two recent articles help put the zero score into perspective.

In the Multi-Ethnic Study of Atherosclerosis (MESA),1 Rifai and colleagues used data from 6814 participants (aged 45 to 84 years at the study start) to identify 3416 with a zero CAC score. Over a median follow-up of 16 years, the zero-score group had only 189 ASCVD events: 91 heart, 88 stroke, and 10 mixed. The overall risk was fewer than five events per 1000 person-years, but higher (in person-years) in those who at baseline had diabetes (8.9), current cigarette smoking (7.3), kidney disease (6.8), and hypertension (5.4). The adjusted risks for both diabetes and smoking approached the >7.5% 10-year risk suggested by the 2018 cholesterol-management guidelines as the threshold for starting statin therapy. Risk went up with higher estimated ASCVD risk despite a zero score. The clinical message? A zero CAC score in the primary prevention setting is really, really good but not perfect, especially in those individuals with other ASCVD risk factors.

A second article dealt with symptomatic patients.2 Out of 23,759 young patients (median age, 58 years) who had coronary CT angiography to evaluate symptoms, 21% had obstructive disease (CAD), and 14% of those with CAD had a zero CAC score. A zero score with obstructive CAD was more common in younger patients and women. Follow-up at 4.3 years found that 30% of events occurred in those with a zero score. The clinical message? With symptomatic patients, a zero score does not mean zero risk, and symptoms are the trump.

References

1. Al Rifai M, Blaha MJ, Nambi V, et al. Determinants of incident atherosclerotic cardiovascular disease events among those with absent coronary artery calcium: Multi-Ethnic Study of Atherosclerosis. Circulation. 2022;145(4):259–267.https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.121.056705

2. Mortensen MB, Gaur S, Frimmer A, et al. Association of age with the diagnostic value of coronary artery calcium score for ruling out coronary stenosis in symptomatic patients. JAMA Cardiol. 2022;7(1):36–44. https://jamanetwork.com/journals/jamacardiology/article-abstract/2785586

This was also published in Practice Update at:https://www.practiceupdate.com/content/determinants-of-incident-atherosclerotic-cardiovascular-disease-events-among-those-with-absent-coronary-artery-calcium/131223/65/2/1