The investigators analyze the impact of exercise and ablation in patients with symptomatic short-persistent atrial fibrillation (Afib) and heart failure with preserved ejection fraction (HFpEF). It is hypothesized that the combination of ablation and exercise better improves peak oxygen consumption (VO2peak) through improvement of peripheral (exercise training) and central (ablation) adaptations.

Exercise intervention will contain a 12-week combined, video-based, supervised, endurance, resistance and respiratory training.

In a feasibility study the investigators analyze the impact of exercise and ablation in patients with symptomatic short-persistent atrial fibrillation and heart failure with preserved ejection fraction. Patients will be randomized into 2 groups: (1) A control group receiving ablation therapy, and (2) a group receiving ablation therapy and a combination of endurance, strength and respiratory training. The investigators will include 20 patients/group. All patients will receive a smart watch to monitor heart rate and trigger ECG recordings during symptomatic episodes. Smart watch monitoring will be done for 4 weeks. Then all patients will receive baseline examination with laboratory markers, lung function testing, echocardiography, measurement of pulse wave velocity, and screening for sleep apnea. All patients will receive simultaneous cardiopulmonary exercise testing (CPET) and exercise right heart catheterization (exRHC) followed by ablation therapy. Patients will then be randomized into a training and control group. After 2 weeks all patients will receive outpatient CPET to assess changes of VO2peak compared to baseline.

The training group will receive home-based, video-supervised exercise training with a combination of endurance, strength and respiratory training (5x/week). The control group will receive standard recommendations on physical activity. Smart watch monitoring will be continued in all groups until the end of the study. After 12 weeks of training intervention, all groups will undergo echocardiography, lung function testing, measurement of pulse wave velocity and exRHC with simultaneous CPET. All patients will receive 24h Holter monitoring at the end of the study. During exRHC lactate kinetics will be analyzed and improvement of lactate thresholds through exercise training will be determined. The primary outcome is the improvement of VO2peak in the groups. Secondary outcomes are improvements in the ratio of pulmonary capillary wedge pressure/cardiac output (PAWP/CO) and mean pulmonary artery pressure/CO (mPAP/CO). Burden of atrial fibrillation in the groups will also be assessed. All groups will receive optimal drug therapy.

The investigators expect that a combined approach of ablation and exercise training will better improve VO2peak through central (ablation) and peripheral (exercise training) adaptations.

Inclusion Criteria:

• Diagnosed heart failure with preserved ejection fraction
• Symptomatic short-persistent atrial fibrillation (diagnosis within 1 year of study inclusion)

Exclusion Criteria:

• Paroxysmal, long-persistent or permanent atrial fibrillation
• Clinically unstable coronary artery disease or acute coronary syndrome
• Physical and/or mental inability to perform exercise testing
• Prior ablation therapy
• Precapillary pulmonary hypertension at rest
• Intracardiac shunts
• Left ventricular ejection fraction <50%
• High-degree valve insufficiency or stenosis (greater than grade 1 at rest)

Information can be received on reasonable request from the principal investigator

The principal investigator (PI) will not receive information on group allocation. Group allocation and data will be saved in a password-secured database, which will not be accessible to the PI.