The goal of clinical trial is to compare AF ablation to pharmacological rhythm management (being rate or rhythm control) in AF patients with signs of atrial cardiomyopathy (as defined by left atrial volume index >34 ml/m2) The main objective it aims to answer is to determine whether AF ablation compared to pharmacological rhythm management in ACMP patients with AF reduces the incidence of the composite primary endpoint of CV death and first CV hospitalization/urgent visit.

The RACE X trial investigates the impact of atrial cardiomyopathy (ACMP) and ablation timing on adverse outcomes in atrial fibrillation (AF) patients. ACMP leads to an atrial substrate less responsive to rhythm control, exacerbating AF recurrence and progression. This trial assesses whether AF ablation versus pharmacological rhythm management reduces the combined primary endpoint of cardiovascular (CV) death and hospitalization in ACMP and AF patients. Secondary objectives include measuring ACMP progression, ACMP-related outcomes, mortality, hospitalizations, AF symptoms, quality of life, and healthcare costs. Exploratory goals involve various additional measurements. This prospective, multicenter, open-label, blinded-endpoint, phase IIIb trial randomizes patients with ACMP and AF to receive either AF ablation or pharmacological rhythm management. Follow-up involves mobile health (mHealth) applications, questionnaires, and heart rhythm monitoring across 13 Dutch hospitals. Ineligible patients undergoing AF ablation join an observational registry. The trial population consists of patients aged 65-80 years with confirmed ACMP and ECG-confirmed AF. With 604 patients and a median 2.5-year follow-up, the trial aims to assign patients equally to each intervention. The primary endpoint is a composite of CV death and hospitalization. Catheter ablation, a safe and efficient technique, minimizes patient burden, and remote follow-up through mHealth reduces site visits. Additional study procedures are integrated into routine care, ensuring a streamlined process.

Inclusion criteria

• Confirmed ACMP (LAVI >34 ml/m2)
• ECG-confirmed AF
• Age: 65-80 years old
• Patients eligible for both treatment strategies judged by the treating physician signed and dated informed consent prior to admission to the trial

Exclusion criteria

• Longstanding (>1 year) persistent or permanent (accepted) AF
• Previous left atrial (LA) ablation or LA surgery
• AF due to a reversible cause (e.g. hyperthyroidism, post-operative AF)
• Recent (<90 days) acute coronary syndrome, stroke/TIA or cardiac intervention (Cardiac interventions include percutaneous coronary intervention, coronary artery bypass grafting, and heart valve repair or replacement (endovascular or surgical))
• Intracardiac thrombus
• HF NYHA III/IV
• Impaired renal function, defined as estimated glomerular filtration rate ≤25 ml/min/1.73m2
• Presence of (or scheduled for) mechanical assist device or heart transplant
• Severe aortic or mitral valve disease
• Complex congenital heart disease
• Life expectancy <1 year
• Currently enrolled in another clinical randomized trial

1:1 by stratitification

endpoints will be adjudicated by a blinded clinical endpoint committee