Red blood cell distribution width as a novel prognostic marker after myocardial revascularization or cardiac valve surgery

Abstract

The red blood cell distribution width (RDW) measures the variability in the size of circulating erythrocytes. Previous studies suggested a powerful correlation between RDW obtained from a standard complete blood count and cardiovascular diseases in both primary and secondary cardiovascular prevention. The current study aimed to evaluate the prognostic role of RDW in patients undergoing cardiac rehabilitation after myocardial revascularization and/or cardiac valve surgery. The study included 1.031 patients with available RDW levels, prospectively followed for a mean of 4.5 ± 3.5 years. The mean age was 68 ± 12 years, the mean RDW was 14.7 ± 1.8%; 492 patients (48%) underwent cardiac rehabilitation after myocardial revascularization, 371 (36%) after cardiac valve surgery, 102 (10%) after valve-plus-coronary artery by-pass graft surgery, 66 (6%) for other indications. Kaplan-Meier analysis and Cox hazard analysis were used to associate RDW with mortality. Kaplan-Meier analysis demonstrated worse survival curves free from overall (log-rank p < 0.0001) and cardiovascular (log-rank p < 0.0001) mortality in the highest RDW tertile. Cox analysis showed RDW levels correlated significantly with the probability of overall (HR 1.26; 95% CI 1.19-1.32; p < 0.001) and cardiovascular (HR 1.31; 95% CI 1.23-1.40; p < 0.001) mortality. After multiple adjustments for cardiovascular risk factors, hemoglobin, hematocrit, C-reactive protein, microalbuminuria, atrial fibrillation, glomerular filtration rate,left ventricular ejection fraction and number of exercise training sessions attended, the increased risk of overall (HR 1.10; 95% CI 1.01-1.27; p = 0.039) and cardiovascular (HR 1.13; 95% CI 1.01-1.34; p = 0.036)mortality with increasing RDW values remained significant. The RDW represents an independent predictor of overall and cardiovascular mortality in secondary cardiovascular prevention patients undergoing cardiac rehabilitation.