Visual Estimate of Coronary Artery Calcium Predicts Cardiovascular Disease in COPD

Abstract

Background: COPD is associated with cardiovascular disease (CVD), and coronary artery calcification (CAC) provides additional prognostic information. With increasing use of nongated CT scans in clinical practice, this study hypothesized that the visual Weston CAC score would perform as well as the Agatston score in predicting prevalent and incident coronary artery disease (CAD) and CVD in COPD.

Methods: CAC was measured by using Agatston and Weston scores on baseline CT scans in 1,875 current and former smokers enrolled in the Genetic Epidemiology of COPD (COPDGene) study. Baseline cardiovascular disease and incident cardiac events on longitudinal follow-up were recorded. Accuracy of the CAC scores was measured by using receiver-operating characteristic analysis, and Cox proportional hazards analyses were used to estimate the risk of incident cardiac events.

Results: CAD was reported by 133 (7.1%) subjects at baseline. A total of 413 (22.0%) and 241 (12.9%) patients had significant CAC according to the Weston (≥ 7) and Agatston (≥ 400) scores, respectively; the two methods were significantly correlated (r = 0.84; P < .001). Over 5 years of follow-up, 127 patients (6.8%) developed incident CVD. For predicting prevalent CAD, c-indices for the Weston and Agatston scores were 0.78 and 0.74 and for predicting incident CVD, they were 0.62 and 0.61. After adjustment for age, race, sex, smoking pack-years, FEV1, percent emphysema, and CT scanner type, a Weston score ≥ 7 was associated with time to first acute coronary event (hazard ratio, 2.16 [95% CI, 1.32 to 3.53]; P = .002), but a Agatston score ≥ 400 was not (hazard ratio, 1.75 [95% CI, 0.99-3.09]; P = .053).

Conclusions: A simple visual score for CAC performed well in predicting incident CAD in smokers with and without COPD.

Trial registry: ClinicalTrials.gov; No.: NCT00608764; URL: www.clinicaltrials.gov.

Keywords: COPD; cardiovascular disease; coronary calcification.

Copyright © 2018 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1

A, The accuracy of coronary artery calcification (CAC) for prevalent coronary artery disease at baseline according to the Agatston and Weston scores was comparable using receiver-operating characteristic analyses: c-indices of 0.74 (95% CI, 0.70-0.79; P < .001) and 0.78 (95% CI, 0.74-0.82; P < .001), respectively. B, In those with COPD, the accuracy was comparable for the two scores: c-indices of 0.75 (95% CI, 0.70-0.80; P < .001) for the Agatston score and 0.76 (95% CI, 0.70-0.81; P < .001) for the Weston score.

Figure 2

Kaplan-Meier curves comparing the Weston visual score with the Agatston score for acute coronary event-free follow-up. After adjustment for age, race, sex, smoking pack-years, FEV1, percent emphysema, and CT scanner type, Weston scores ≥ 7 compared with scores < 7 were associated with a shorter time to first coronary event (adjusted hazard ratio: 2.16 [95% CI, 1.32-3.53]; P = .002). In contrast, compared with Agatston scores < 400, a score ≥ 400 was not associated with a shorter time to first event (adjusted HR, 1.75 [95% CI, 0.99-3.09]; P = .053).