Patients reporting to the investigators' clinic for in- and outpatient consultation and a HFA-PEFF score of 2-4 points will be recruited if their dyspnea is not sufficiently explained by other causes than HFpEF. Patients will undergo a baseline clinical exam, transthoracic echocardiography with measurement of diastolic parameters, and ECG. NYHA class will be reported, standard lab works (NTproBNP, GFR, CRP, Hb, PLT, blood gas analysis) will be taken. The number of patients with a PAWP increase in right heart catheterization (brachial access under sonographic guidance) from a resting value of <15mmHg to >25mmHg during stress testing will be assessed across the four interventions. During bicycle ergometry (semi-supine position) spiroergometric data and gas exchange variables (cardiopulmonary exercise testing) will be co-assessed. Between the testing modalities a 10-minute break will allow hemodynamic variables to normalize.
Patients with an intermediate risk (HFA-PEFF score 2-4 points) for heart failure with preserved ejection fraction (HFpEF) will be further investigated with invasive right heart catheterization. All patients with a resting pulmonary artery wedge pressure (PAWP) <15mmHg will undergo the following stress test modalities in a randomized order: (1) bicycle ergometry, (2) dynamic handgrip exercise, (3) 500ml fluid challenge over 5 minutes, (4) leg raise testing. Exercise induced HFpEF will be diagnosed if PAWP rises to >25mmHg.