FUNCTIONAL PHENOTYPES OF REDUCED EXERCISE TOLERANCE IN MEN: A COMPREHENSIVE ASSESSMENT OF CARDIOVASCULAR FUNCTIONAL RESERVE

Objective. To assess cardiovascular functional reserve in men and identify the major phenotypes of exercise intolerance based on a comprehensive evaluation of clinical and instrumental parameters. Materials and Methods. At the first stage, 400 men without a previously established diagnosis of heart failure with preserved ejection fraction (HFpEF) were examined. One hundred participants with relevant symptoms, cardiovascular risk factors, and/or potential indicators of reduced functional reserve were selected for an in-depth assessment. The protocol included clinical evaluation, the six-minute walk test, exercise stress echocardiography, and cardiopulmonary exercise testing when corresponding data were available. Parameters of left ventricular diastolic function and global longitudinal strain, right ventricular function, chronotropic response, and gas exchange were analyzed. Functional stratification was performed according to predefined pathophysiological criteria. Results. Five functional phenotypes were identified: preserved functional reserve (21%), diastolic (17%), impaired right ventricular–pulmonary arterial coupling (15%), chronotropic (14%), and peripheral (33%). The phenotypes differed in exercise tolerance, changes in E/e′, TAPSE/SPAP ratios, heart rate response, and peak oxygen uptake. The lowest Peak VO₂ values were observed in the peripheral phenotype, whereas the most pronounced increase in E/e′ during exercise was observed in the diastolic phenotype. Conclusion. Comprehensive exercise-based assessment makes it possible to characterize the heterogeneity of functional limitations in the examined men and distinguish phenotypes associated with different presumed pathophysiological mechanisms. Further studies are required to establish the diagnostic and prognostic value of the proposed stratification approach.