The metabolic syndrome, its component risk factors, and progression of coronary atherosclerosis.

Background: The mechanism that confers adverse cardiovascular prognosis in patients with the metabolic syndrome (MetS) remains unclear. We sought to investigate the association of MetS and its component risk factors with progression of coronary atherosclerosis.

Methods: We performed a systematic review of 3459 patients who participated in 7 clinical trials that monitored coronary atheroma progression with intravascular ultrasonography. Patients with or without MetS were compared with regard to clinical characteristics, coronary atheroma burden at baseline, and change on serial evaluation. Relationships between plaque progression (> or =5% increase in percent atheroma volume [PAV]), MetS, and its component risk factors were investigated.

Results: The metabolic syndrome was highly prevalent and was associated with greater progression of PAV (+0.51% +/- 0.23% vs +0.23% +/- 0.24%; P = .003). Multivariable analysis showed that MetS was associated with a greater likelihood of undergoing progression of PAV (adjusted odds ratio [OR], 1.25; 95% confidence interval [CI], 1.05-1.48; P = .01). When the individual components were used in the model instead of MetS, hypertriglyceridemia (OR, 1.26; 95% CI, 1.06-1.49; P = .008) and a body mass index of 30 or higher (1.18, 1.00-1.40; P = .05) predicted progression of PAV. However, after adjusting for its individual components, MetS was no longer an independent predictor (OR, 1.04; 95% CI, 0.79-1.37; P = .79).

Conclusion: Although accelerated disease progression is observed in the setting of MetS, this is owing to the presence of individual component risk factors rather than to the presence of the syndrome itself.