Diagnostic Accuracy of Carotid Intima-Media Thickness to Detect Coronary Atherosclerosis. Usefulness in Clinical Practice

pp 105-107

Abstract

Background
Carotid intima-media thickness (CIMT) is an independent marker of cardiovascular risk. Coronary artery calcium score (CACS) is better than CIMT to predict coronary artery disease; yet, few patients have access to this evaluation in our country due to its high cost.

Objectives

The aim of this study was: 1) to evaluate the diagnostic accuracy of CIMT to detect CACS >0. 2) To determine an optimal cut-off point of CIMT to discriminate between the presence and the absence of coronary artery calcium.

Methods

We conducted a cross-sectional descriptive study of consecutive samples obtained in the outpatient clinic of cardiovascular prevention. Mean and maximum CIMT were measured using carotid Doppler ultrasound. Carotid artery atherosclerotic plaque (CAP) was evaluated with a 64-row multidetector computed tomography. The diagnostic accuracy of CIMT to detect CACS >0 was determined by ROC analysis.

Results
A total of 202 consecutive subjects participating in a primary prevention program were included. Population characteristics were  mean ± standard deviation): age 57±13 years, female gender: 49%, smokers: 13%, statins: 37%, diabetes mellitus: 13%, Framingham risk score in non diabetics: 9%±7%, mean CIMT: 0.953±0.342 mm, maximum CIMT: 1.383±0.679 mm, prevalence of carotid artery atherosclerotic plaque: 37% and of CACS >0: 62%. The correlations between mean and maximum CIMT and CACS were poor (r=0.393 and r=0.376, respectively). The area under the ROC curve of maximum CIMT was 0.822 (95% CI 0.763-0.880) and that of mean CIMT was 0.829 (95% CI 0.771-0.888). The optimal cut-off point of maximum CIMT to discriminate between CACS >0 or CACS = 0 was ≥1.01 mm and sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 78%, 75%, 83% y 67%, respectively. The optimal cut-off point of mean CIMT to discriminate between CACS>0 or CACS = 0 was ≥0.82 mm and sensitivity, specificity, PPV and NPV were 77%, 78%, 85% and 67%, respectively.

Conclusions
In this low-risk population, the diagnostic accuracy of CIMT to detect CACS >0 was moderate. A “normal” carotid Doppler ultrasound did not exclude the presence of subclinical coronary artery atherosclerosis. These results might improve selection of patients undergoing CACS to stratify cardiovascular risk.