A low or zero coronary artery calcification (CAC) score does not rule out risk of sudden cardiac death, especially in younger people, according to a large autopsy study. Writing in JACC: Cardiovascular Imaging, researchers discovered that fatal plaque erosion often occurs without detectable calcification and disproportionately affects younger individuals under 50. “Our analysis revealed a clear hierarchy of CAC burden: it was lowest in plaque erosion, intermediate in rupture, and highest in stable plaque and calcified nodules,” the authors wrote. “Most erosions (90%) had none or mild CAC whereas the majority of stable plaques (∼60%) exhibited moderate to severe CAC.” Universal risk marker The study questions the view that CAC is a universal marker of risk. While higher scores independently predicted plaque rupture and stable plaque, erosion was not significantly linked to calcium buildup. “The central clinical implication is that a low or zero CAC score does not preclude sudden death risk, particularly in younger individuals susceptible to plaque erosion,” wrote the authors, led by Teruo Sekimoto, MD, PhD, from Showa Medical University in Tokyo, Japan. The investigation looked at 3,130 hearts from the CVPath sudden coronary death registry, comparing CAC burden with the plaque types most often responsible for fatal events: rupture, erosion, calcified nodules and stable plaque. The results revealed that CAC’s predictive value varies significantly depending on plaque pathology. Non-calcified plaques The research team explained that non-calcified plaques may be especially dangerous in younger adults, providing an explanation for why some patients with a CAC score of zero still suffer fatal outcomes. “Our findings provide a pathological explanation for clinical observations that a CAC score of zero can still confer some element of risk, demonstrating that nearly half of fatal erosions in the young occur without detectable calcification,” researchers concluded. While the study was limited by its autopsy-based design, it remains the largest of its kind to date. The authors concluded that personalized risk assessments, beyond reliance on CAC alone, are needed to better identify vulnerable patients. Sources: Sekimoto T, Shiraki T, Tanaka T, et al. Coronary Artery Calcification Scoring and Plaque Types in Sudden Deaths. J Am Coll Cardiol Img. 2025. [Article in Press]. Image Credit: Ulazislau – stock.adobe.com