Background: The metabolic syndrome confers an increased risk of major cardiovascular events in individuals initially free from coronary heart disease (CHD). Presently, approximately 25% of the US population possesses the metabolic syndrome as defined using the National Cholesterol Education Program (NCEP) criteria. We sought to assess the impact of the metabolic syndrome and its individual components on intermediate-term and long-term outcomes in patients with CHD.
Methods: The CASS registry represents a database of 24,958 patients with suspected or proven CHD who underwent cardiac catheterization between 1974 and 1979. Mean long-term follow-up was 12.6 +/- 5.1 years. Metabolic syndrome was defined using modified definitions of the NCEP and World Health Organization (WHO) because high-density lipoprotein cholesterol measures were not available.
Results: We identified 3279 and 1080 patients with metabolic syndrome using our modified NCEP and WHO definitions, respectively. Adjusted long-term all-cause death was higher in patients with metabolic syndrome (hazard ratio [HR] 1.21, 95% CI 1.14-1.29; HR 1.56, 95% CI 1.43-1.70 for NCEP and WHO criteria, respectively). Similarly, long-term adjusted risk of cardiovascular death and intermediate-term risk of morbidity and mortality were higher in patients with the metabolic syndrome. Fasting blood glucose > or = 110 mg/dL was responsible for most of the increased risk associated with the metabolic syndrome (adjusted HR 1.47, 95% CI 1.39-1.56).
Conclusions: The metabolic syndrome confers a higher risk of long-term death in patients with preexisting CHD, and dysglycemia appears to be responsible for most of the associated risk.