Relationship of Cardiopulmonary Exercise Capacity to Coronary Microvascular Function and Body Composition in Patients with Suspected Heart Failure with Preserved Ejection Fraction.

BACKGROUND: Exercise intolerance in heart failure reflects heterogeneous mechanisms, including coronary microvascular dysfunction (CMD), obesity and sarcopenia. The aim of this study was to investigate the relationships between cardiopulmonary exercise capacity, coronary microvascular function and body composition in patients with suspected heart failure with preserved ejection fraction (HFpEF). METHODS: In this single-centre cross-sectional study, consecutive patients presenting with chest discomfort or dyspnoea and an intermediate or high probability of HFpEF were enrolled. All patients underwent body composition analysis, adenosine stress echocardiography for coronary flow reserve (CFR) and cardiopulmonary exercise testing to assess peak oxygen consumption (VO2 peak). RESULTS: Of the 101 patients (mean age 63 years; 52.0% women), CMD (CFR <2.5) was present in 40.6%. Mean VO2 peak was 23.0 ± 5.3 ml/min/kg. Patients with lower VO2 peak (<23 ml/min/kg) had higher visceral fat area and percentage body fat. VO2 peak correlated positively with CFR (r=0.344, p<0.001) and septal e' velocity and inversely with E/e'. Skeletal muscle mass index correlated positively with VO2 peak predominantly in obese patients (BMI ≥25 kg/m2). In multivariable analysis, both CFR and degree of body fat remained independent correlates of VO2 peak. CONCLUSION: In patients with suspected HFpEF, cardiopulmonary exercise capacity is closely associated with left ventricular diastolic function, coronary microvascular function and body composition. Preserved skeletal muscle mass may mitigate the adverse impact of obesity on exercise performance. These findings highlight the importance of integrated assessment of CMD and body composition and support targeted lifestyle and exercise interventions to improve functional capacity in HFpEF phenotypes.