The Heart Failure With Preserved Ejection Fraction (HFpEF) Pathophysiology Study.

The study addresses the hypothesis that a gradual build-up in arterial resistance and microvascular endothelial dysfunction due to common comorbidities such as hypertension and diabetes mellitus, on top of age related vascular and cardiac changes (mainly fibrosis and hypertrophy), is responsible for HFpEF. The HFpEF syndrome is commonly seen in elderly subjects (often females) with hypertension and diabetes. The investigators will investigate the vascular function, cardiovascular performance and myocardial fibrosis in different cohorts of subjects to try and prove this hypothesis. There will be 5 groups of subjects, all ≥ 70 years of age, as follows: A) Normal healthy volunteers without major comorbidities including hypertension or diabetes B) Patients with hypertension only (without diabetes mellitus) C) Patients with hypertension AND diabetes mellitus D) Patients with HFpEF. E) A parallel group of patients with Heart Failure with reduced Ejection Fraction (HFrEF) group. Arterial resistance measured by pulse wave velocity will be the primary measure and will be compared between groups A to D. A separate comparison will be made between groups D and E. Other secondary measures will focus on endothelial function (Laser Doppler measurements) and other cardiovascular performance measures (peak VO2 by CPEX, 6-minute walk distance). Bloods samples will be taken for NT-proBNP, high sensitivity Troponin T, Galectin 3 and also stored for testing later for vascular biomarkers.