Association of cystatin C with mortality, cardiovascular events, and incident heart failure among persons with coronary heart disease - Data from the Heart and Soul Study

Background - Serum creatinine and related estimating equations predict cardiovascular events and mortality among persons with coronary heart disease (CHD). Cystatin C is a novel and sensitive endogenous marker of kidney function. Whether cystatin C concentrations are associated with adverse events among ambulatory persons with CHD is unknown. Methods and Results - Nine hundred ninety ambulatory persons with CHD were categorized into quartiles of serum cystatin C at inception, with <= 0.91 mg/ L constituting the lowest quartile ( I) and >= 1.30 mg/ L constituting the highest ( IV). Cox proportional hazards models evaluated time to all-cause mortality, cardiovascular events ( composite of CHD death, myocardial infarction, and stroke), and incident heart failure. After a median follow-up of 37 months, 132 participants ( 13%) died, 101 ( 10%) had cardiovascular events, and 57 ( 7%) had incident heart failure. Compared with participants in the lowest cystatin C quartile, those in the highest quartile were at increased risk of all-cause mortality ( hazard ratio, 3.6; 95% CI, 1.8 to 7.0), cardiovascular events ( hazard ratio, 2.0; 95% CI, 1.0 to 3.8), and incident heart failure ( hazard ratio, 2.6; 95% CI, 1.0 to 6.9) in analyses adjusted for traditional cardiovascular risk factors. Cystatin C in the highest quartile predicted similar risk for these outcomes among participants with lower ( <= 60 mL/ min per 1.73 m(2)) or higher estimated glomerular filtration rate and among participants with or without microalbuminuria. Conclusions - High cystatin C concentrations predict substantial increased risks of all-cause mortality, cardiovascular events, and incident heart failure among ambulatory persons with CHD. This risk is not completely captured by measures of kidney function routinely used in clinical practice.