# Association of Quantitative Coronary Artery Calcium Density Subtype Volumes With Major Adverse Cardiovascular Events

## TL;DR

This study shows that low-density coronary artery calcium is a strong predictor of future heart problems, improving risk assessment in patients.

## Contribution

The study introduces a novel method of analyzing coronary artery calcium density subtypes to predict cardiovascular events more accurately.

## Key findings

- Low-density CAC volume independently predicted major adverse cardiac events across three patient groups.
- Low-density CAC improved risk discrimination and reclassification compared to conventional methods.
- Intermediate and high-density CAC volumes were not significantly associated with MACE.

## Abstract

Growing evidence has demonstrated that low density coronary artery calcification (CAC) is associated with a higher risk of cardiovascular events.

We aim to explore the relationship between CAC volumes at predefined densities, assessed by CAC volume according to CAC Hounsfield unit (HU), and major adverse cardiac events (MACEs).

We evaluated 3 patient groups with no prior coronary artery disease history who underwent an electrocardiogram-gated noncontrast computed tomography scan for CAC scanning (CAC group, n = 2,028) or as part of a cardiac imaging test: single-photon emission computed tomography (SPECT)-myocardial perfusion imaging (SPECT group, n = 2,782), and positron emission tomography (PET)-myocardial perfusion imaging (PET group, n = 2,366). CAC subtype volumes of low, intermediate, and high density based on HU cutoff (low: 130-199 HU, intermediate: 200-399 HU, and high: ≥400 HU). MACE included mortality, myocardial infarction, unstable angina, and late revascularization.

During a median 4.3 years (interquartile ranges: 2.6-12.8) follow-up duration, 1,033 MACE occurred (14.4%). In multivariable analysis, low-density CAC volume was independently predictive of MACE (log-transformed; CAC group: HR: 1.65; 95% CI: 1.05-2.60; SPECT group: HR: 1.41, 95% CI: 1.02-1.94; PET group: HR: 1.34, 95% CI: 1.11-1.61; P < 0.05), whereas intermediate and high-density volumes were not (P > 0.05). Density CAC volumes improved discrimination and reclassification among all 3 groups (CAC, SPECT, and PET groups: global chi-square improvement: 9.1, 16.1, and 16.6, respectively, P < 0.01; net reclassification index: 47.3, [95% CI: 33.2-61.4], 49.6 [95% CI: 36.8-62.4] and 15.4, [95% CI: 5.9-24.9], respectively, P < 0.01).

Low-density HU volume was independently associated with an increased MACE risk and improved discrimination and reclassification over conventional approaches in a broad spectrum of individuals undergoing CAC scanning.