Aortic stiffness (AS), defined as the elastic resistance to deformation resulting from complex interactions between vascular smooth muscle cells and the extracellular matrix is a marker of increased cardiovascular (CV) risk and mortality. Age, hypertension, diabetes, atherosclerosis, and chronic kidney disease may represent the most important contributors to its increase.¹ A low cardiorespiratory fitness, estimated through peak V02 value obtained during a cardiopulmonary exercise test (CPET), has been also shown to represent an independent marker of adverse CV outcome.² Nowadays, only few studies explored the correlation between arterial stiffness and cardiorespiratory fitness in patients undergoing cardiopulmonary exercise testing.3–6 The aim of the present study was to evaluate the association between two markers of AS, pulse wave velocity (PWV) and augmentation index (AI), on different CPET-derived data, such as ventilatory efficiency (VE/VCO2 slope), CV efficiency (VO2/WR slope), and oxygen uptake extraction slope (OUES).
This prospective cross-sectional study included individuals who underwent CV evaluation at ‘CV Prevention Unit of Fondazione Don Gnocchi, Parma’ from 2017 to 2018. Our ethics committee on human research approved the collection of data in accordance with the Declaration of Helsinki after having obtained written informed consent from all the subjects. Incremental and maximal cardiopulmonary tests were performed with the Cosmed Quark C-PET system (COSMED, Rome, Italy) until maximal perceived exertion; cardiorespiratory fitness was evaluated as peak VO2 (mL/kg/min) (mean oxygen uptake over the last 30 s of exercise). Before CPET examination, pulse wave analysis was performed using the Vicorder (Skidmore Medical, Bristol, UK) with oscillometric technique to detect the pulse waveform between the two recording sites.⁶,⁷ Measurements were obtained by using a 10-cm-wide cuff around the right upper thigh to detect the femoral pulse and a 10-cm-wide cuff around the arm to detect the right brachial pulse. The cuffs were automatically inflated simultaneously and pulse waveform was recorded for 3–5 s, while the patient was in supine position, before freezing the display screen and obtaining the pulse wave analysis. Carotid-femoral PWV was calculated by the formula: PWV (m/s) = distance between measurement locations (m)/transit time. Augmentation index was calculated by the formula: AI (%): (Augmentation pressure/Pulse pressure) × 100.⁸,⁹ Differences among groups were tested by ANOVA, with Least-Significant Difference post-hoc analysis. The Shapiro–Wilk test was used to check the normality distribution of continuous variable. Linear regression analysis was performed and the relationship between potential predictors and main outcome measures was analysed using stepwise logistic regression models including different covariates. Statistical significance was set at P < 0.05.