Subendocardial viability ratio as a predictor of cardiovascular events and mortality in hypertensive patients

Objective: The subendocardial viability ratio (SEVR) can usefully estimate the degree of myocardial perfusion relative to left-ventricular workload and is calculated from analysis of aortic pressure waves, which can be evaluated by arterial tonometry. Aim of this study was to determine the predictive ability of tonometry-derived SEVR for mortality and major cardiovascular events (MACEs) in treated hypertensives and to determine the optimal SEVR cut-offs for these endpoints. Design and method: 336 hypertensive patients (mean age±standard deviation 63.2±14.0 years, 53.0% females) referring to a hypertension centre were enrolled and followed-up for 9.2±2.0 years. SEVR was estimated non-invasively by analysing the carotid pressure curve recorded by a PulsePen (DiaTecne, Milan) arterial tonometer, and calculated as the ratio between subendocardial oxygen supply (represented by the area between aortic and ventricular curves in the diastolic phase) and demand (represented by the area below the ventricle pressure curve in the systolic phase). Mortality and MACE cut-off values were calculated using the Youden Index on ROC curves and predictive ability was evaluated using Cox-regression models. Results: Mean SEVR at baseline was 105.3±25.8%; 54 deaths and 66 MACEs occurred in the follow-up. Optimal SEVR cut-offs for mortality and MACEs were respectively 88% and 82.5%. A SEVR below these cut-offs significantly predicted mortality and MACEs in univariate Cox-regression model (mortality risk ratio 2.22; 95% confidence interval (CI) [1.29-3.80], p = 0.004, MACEs risk ratio 2.26; 95%CI [1.34-3.79], p = 0.002), and in a model corrected for age, sex, mean blood pressure and heart rate (mortality risk ratio 2.09; 95%CI [1.07-4.10], p = 0.032, MACEs risk ratio 2.05; 95%CI [1.08-3.89], p = 0.029). Conclusions: SEVR derived from arterial tonometry may be a useful predictor of mortality and MACEs in hypertensive patients.