Clinical Phase 2 Trial of AP31969 Versus Placebo for Rhythm Control of Atrial Fibrillation

The key goal of this clinical trial is to assess the effectiveness of different doses of AP31969 in lowering Atrial Fibrillation (AF) burden and its safety.

Participants will be randomly assigned to one of the following groups:

• AP31969 at 100 mg, 200 mg, or 350 mg doses
• AP31969 500 mg (not included at the trial start)
• Placebo (inactive treatment and has no active properties). The placebo group serves as the comparator for AP31969. All treatments are given orally, twice daily.

The trial includes 3 periods: screening (up to 4 weeks), treatment (12 weeks), and follow-up (30 days). The duration of the trial for a participant is approximately 20 weeks.

Participants will receive an implantable loop recorder and undergo assessments during the visits at specific times, for example blood and urine analyses, and electrocardiogram.

Inclusion criteria

• Willing and able to provide written informed consent.
• Age 18 or older.
• ECG documented diagnosis of paroxysmal or persistent AF.
• AF history at screening indicating an expected AF burden of 1-90%, i.e., at least 1 self-terminating AF episode within 4 months prior to the screening visit.
• AF burden of ≥ 1% and ≤ 90% assessed with an ECG patch device during the screening period prior to the randomisation visit.
• Investigator and participant agreement to avoid non-trial related rhythm control intervention for the duration of the trial, including:

• Antiarrhythmic drug class I and/or III (including amiodarone)
• Electrical or pharmacological cardioversion
• AF ablation procedure
• Willing to have a loop recorder implanted.

Exclusion criteria

• Prior AF ablation procedure other than pulmonary vein isolation (PVI) only.
• Any of the following events within 4 weeks prior to the screening visit: Myocardial infarction, Unstable angina pectoris, Stroke or transient, ischaemic attack, Percutaneous coronary intervention (PCI), Coronary artery bypass graft (CABG), Peripheral revascularisation procedure.
• Cardiac pacing device e.g. pacemaker and cardiac resynchronization therapy device with atrial or ventricular pacing for > 5% of the time or existing implantable loop recorder.
• Heart failure, New York Heart Association class III (3) or IV (4).
• Left ventricular ejection fraction < 40% based on imaging (e.g. echocardiography) performed within 6 months prior to or during the screening visit.
• Clinically significant valvular heart disease, including severe aortic stenosis, severe mitral regurgitation and/or severe mitral stenosis, in the opinion of the investigator.
• QTc (Fridericia, QTcF) interval > 450 ms for males and > 470 ms for females at screening.
• eGFR <60 mL/min /1.73 m² based on creatine and CKD-EPI formula
• Use of antiarrhythmic drug class I and/or III within 7 days or, for amiodarone, within 3 months prior to the screening visit.