Carotid intima-media thickness (cIMT) is an ultrasound marker of early atherosclerosis.  Increasing cIMT thickness has been shown to correlate with an increased risk of subsequent cardiovascular events in general populations, independent of other major risk factors.  However, whether a change in cIMT thickness over time affects the risk of cardiovascular events has not been systematically investigated.  The first stage of the PROG-IMT project (individual progression of carotid intima media thickness as a surrogate of vascular risk) analysed the association of cIMT progression with the risk of cardiovascular events on a large dataset derived from general populations.

For this meta-analysis, the authors initially identified general population studies that assessed cIMT at least twice and followed up participants for myocardial infarction (MI), stroke, or death; patients with a previous history of MI or stroke were excluded.  36,984 participants from 16 eligible studies were included.  Over a mean follow-up of 7.0 years, 1519 MIs, 1339 strokes, and 2028 combined endpoints (MI, stroke, or vascular death) occurred.  When adjusted for vascular risk factors, mean common carotid IMT progression was associated with a hazard ratio (HR) of 0.98 (0.95-1.01) for the combined endpoint.  However, the mean cIMT was found to associate with cardiovascular risk (HR 1.16).

Conclusions:

This study found no association between cIMT progression and cardiovascular risk, therefore questioning the use of this technique for cardiovascular screening or as a biomarker in clinical trials.

• Lorenz MW, Polak JF, Kavousi M et al.  Carotid intima-media thickness progression to predict cardiovascular events in the general population (the PROG-IMT collaborative project): a meta-analysis of individual participant data.  Lancet 2012;379:2053-62