Red Blood Cell Distribution Width as a Prognostic Factor in Patients Undergoing Transcatheter Aortic Valve Implantation

Background: Red blood cell distribution width (RDW), which is routinely reported in complete blood counts, is a measure of the variability in size of circulating erythrocytes. RDW is an independent predictor of prognosis in patients with cardiovascular diseases. We evaluated the short- and long-term prognostic value of RDW in a large cohort of TAVI patients.

Methods: The impact of RDW on outcome was determined prospectively in 1,029 consecutive patients with severe aortic stenosis (AS) undergoing transfemoral TAVI. The cohort was divided into 2 groups according to RDW above and below 15.5%. Collected data included patient characteristics, medical background, left ventricle ejection fraction (LVEF), frailty score, Society of Thoracic Surgeons (STS) score, periprocedural laboratory results and long term (up to 7.5 years) clinical outcomes.

Results: The mean age (±SD) was 83.1±6.3 years, mean STS score was 4.2±3.1% and mean estimated LVEF was 55.7±8.4%. Mean pre-TAVI RDW levels were 15.3±3.2%. Patients with RDW≤15.5% (n=683) and RDW>15.5% (n=346) had a 1-year mortality rate of 6% and 17%, respectively (P=0.001) and a 5-year mortality rate of 20% and 38%, respectively (P<0.001). Baseline RDW>15.5% was independently associated with all-cause mortality (HR 1.83, 95% CI 1.44 to 2.32, p<0.001).

Conclusions: Elevated RDW is a strong independent marker and predictor of short and long-term mortality following TAVI, that might present a relevant future supplement to current preprocedural risk scores. Additional research is needed to clarify the mechanisms responsible for this finding.