Reduced kidney function estimated by cystatin C and clinical outcomes in hypertensive patients with coronary artery disease: association with homocysteine and other cardiovascular risk factors.

Aims: To evaluate the association between serum cystatin C and homocysteine concentrations, cardiovascular risk factors and cardiovascular events in hypertensive patients with coronary artery disease (CAD).

Methods: 260 patients with hypertension and CAD (mean age 56.9 +/- 9.3) were included. During a mean 40-month follow-up the combined end-point of death from all causes, non-fatal myocardial infarction and stroke or coronary revascularization was assessed.

Results: Subjects in the highest serum cystatin C quartile (>103.4 nmol/l) as compared with the lowest were older, were characterized by a higher frequency of multivessel CAD, higher levels of homocysteine (13.2 +/- 5.2 vs. 11.4 +/- 4.2 micromol/l; p < 0.01), fibrinogen and high-sensitivity C-reactive protein and by an increased intima-media thickness. Combined end-point occurred twice as frequently in the 4th quartile of serum cystatin C as compared with the 1st quartile (10.8 vs. 20.3%; p = 0.11). In an univariate analysis, but not in a multivariate model, cystatin C concentration predicted the combined end-point (Exp(B) = 1.096; p < 0.05).

Conclusion: In hypertensive patients with CAD, serum cystatin C level was independently associated with the extent of CAD, homocysteine plasma level and traditional vascular risk factors. However, serum cystatin C concentration did not independently predict the combined end-point.