Outcome Associations of Carotid-Femoral Pulse Wave Velocity Vary With Different Measurement Methods

BACKGROUND The impact of various methods of travel distance estimation on the prognostic value of pulse wave velocity (PWV) and on the adequacy of cut-offs has never been addressed within a single population of hypertensive patients. METHODS Four carotid-femoral PWVs were calculated from four different travel distances (Direct, Real, Subtracted, and Estimated) divided by the same travel time in 426 hypertensives (mean age 51.2 +/- 13.8 years, mean systolic blood pressure 155.6 +/- 21.1 mm Hg). The incidence of death from any cause and major cardiovascular events was studied. PWV predictive accuracies were determined using C-index analysis. Hazard ratios (HRs) associated with specific values of PWV were determined with Cox model analyses using cubic splines. RESULTS Mean PWV ranged from 8.3 +/- 2.3 m/s for the Subtracted one to 11.6 +/- 3.0 m/s for the Direct one (P < 0.001). When included as continuous variables in a Cox model, the four PWVs were significantly associated with outcome (all P < 0.001), and had similar C-index (0.608-0.617). In multivariable analysis, the HR calculated for a Direct PWV of 12 m/s was neutral (HR = 1.02). In contrast, the same analysis provided HR ranging from 1.79 to 2.90 with the other PWVs. CONCLUSIONS Different travel distances markedly impact PWV values and prognostic cut-offs. PWV cut-offs should consequently be ascertained jointly with the method of measurement used. There is an urgent need for standardization of PWV assessment before implementing this parameter in the routine management of hypertensives.