Maximum plaque height in carotid ultrasound predicts cardiovascular disease outcomes: a population-based validation study of the American Society of Echocardiography’s grade II–III plaque characterization and protocol

The presence of carotid arterial plaque by ultrasound enhances cardiovascular risk stratification beyond traditional risk factors. However, plaque quantification techniques require further outcomes-based investigation. The purpose of this study was to evaluate the utility of a focused carotid ultrasound protocol and novel plaque grading system developed by the American Society of Echocardiography (ASE). A retrospective analysis of 514 outpatients who were referred for coronary angiography between 2011 and 2014 was performed using a province-sponsored health database. All participants prospectively received a focused carotid ultrasound. Maximum plaque height (MPH) of arterial carotid plaque was quantified, using the grade II–III plaque definition of MPH ≥ 1.5 mm for stratification, according to recent ASE recommendations. Participants were followed for 1.33–5.11 years (average follow-up = 3.60 ± 1.65 years) to identify the occurrence of cardiovascular events. Major events (death, myocardial infarction [MI], stroke, and transient ischemic attack [TIA]) were correlated to MPH. Participants with MPH ≥ 1.5 mm were more likely to experience stable angina, coronary artery bypass grafting, and stress testing at both 1-year and total follow-up. After adjusting for cardiac risk factors, increased MPH was shown to be predictive for TIA (odds ratio [OR] = 1.33, 95% confidence interval (CI) = 1.01–1.75); p = 0.04), whereas the odds of non-ST-elevation MI (OR = 1.55, 95% CI = 0.99–2.43; p = 0.06) approached significance. Using Kaplan–Meier survival analysis, MPH ≥ 1.5 mm demonstrated good separation for the composite outcome of death, MI, stroke, and TIA over total follow-up (p = 0.02). This rapid, office-based quantification of MPH in carotid ultrasound may serve as a stratification tool for predicting major cardiovascular events.