Carotid Intima-Media Thickness Measurements in Intervention Studies

Abstract

Background-Carotid intima-media thickness (CIMT) measurements are currently widely used in randomized controlled trials (RCTs) to study the efficacy of interventions. In designing a RCT with CIMT as a primary outcome, several ultrasound options may be considered. We discuss the various options and provide a pooled estimate of CIMT progression. In addition, we quantify the effect of these choices on the sample size for a RCT. Summary of Comment-To estimate the average CIMT progression rate, we performed a pooled analysis using CIMT progression rates of control groups from published RCTs. The pros and cons of the following ultrasound options are discussed: which arterial segments may be studied; whether near and far wall CIMT measurements should be performed; whether a single image (1 angle of interrogation) or multiple images (more angles of interrogation) should be used; whether a manual or an automated edge detection reading system should be used; and whether images should be read in a random fashion or in batches. The pooled analysis showed an annual rate of change in mean common CIMT of 0.0147 mm (95% CI, 0.0122 to 0.0173) and in mean maximum CIMT of 0.0176 mm (95% CI, 0.0149 to 0.0203). Conclusions-Given the current evidence together with our experience with recently developed ultrasound protocols, we favor the use of mean maximum CIMT rather than mean common CIMT as the primary outcome measure in RCTs designed to evaluate the efficacy of pharmacological and nonpharmacological interventions in carotid artery atherosclerosis.

Reproducibility and Reliability of Atherosclerotic Plaque Volume Measurements in Peripheral Arterial Disease with Cardiovascular Magnetic Resonance

“…Using carotid intimal medial thickness measurements as a surrogate efficacy end-point, Bots et al reported that 468 patients would be required to detect a treatment effect of 30% (power 0.80) (33). Three-dimensional ultrasound of plaque in the carotids would require fewer patients to demonstrate efficacy, yet a recent study reported that 203 patients would still be needed to detect a 10% change in plaque volume (power = 0.90) measured over a three month period (34).…”

Renal resistive index and cardiovascular organ damage in a large population of hypertensive patients

“…The end-diastolic intima-media thickness (IMT) of the far wall of the middle segment of both common carotid arteries, defined by a simultaneous electrocardiographic recording, was measured 1 cm caudal to the bulb, as the distance between the lumen-intima interface and the media-adventitia interface. 13,14 Each measurement was calculated by taking the average of three readings. Intima-media thickening of the common carotid arteries was defined as an average IMT X0.9 mm.…”

The clinical significance of carotid intima-media thickness in cardiovascular diseases: a survey in Beijing

“…Other recent studies demonstrated that the association between near-wall CIMT and stroke or MI was as strong as that found for far-wall CIMT, and near-wall CIMT measurement can be obtained with sufficient reproducibility in a considerable proportion of the participants. 18 The combined CIMT measurements of near and far walls showed the strongest association, and may enhance precision without loss of validity. 16 In summary, although most of the carotid lesions locate at CB, the combined measurement of IMT at CCA, CB and ICA shows the most significance in prevalent cardiovascular events.…”

“…In some researches, CCA-IMT has shown to predict future cardiovascular events as well as mean CIMT. 18 Results from the Pravastatin, Lipids, and Atherosclerosis in the Carotid Arteries II even showed that IMT at the far wall of CCA was significantly correlated with progression or regression of disease other than the aggregate measurements at near and far walls of CCA, CB and ICA. 19 However, the CHS, the Rotterdam study and some other studies showed that CB-IMT was more closely related to coronary atherosclerosis, existing atherosclerotic diseases and major established risk factors compared with CCA-IMT.…”

“…The combination of IMT at CCA and ICA correlates more strongly with existing cardiovascular diseases than either taken alone. 1,20,21 Bots ML et al 18 also favoured the use of combined CIMT rather than CCA-IMT as the primary outcome measures to evaluate the efficacy of interventions in carotid atherosclerosis after a pooled analysis. In our study, the mean CIMT at multiple extracranial carotid sites (CCA, CB and ICA, near and far walls, and left and right sides) was found to be more strongly associated with cardiovascular events than the IMT from individual segments, which further ascertained the value of approaches for determining CIMT in combination.…”