Reversal of Atrial Substrate to Prevent Atrial Fibrillation Cohort Study

Randomized clinical trials remain the gold standard for determining the efficacy of an intervention, however, it is well known that patients will decline participation in clinical trials for various reasons. It is critical to understand outcomes of patients who are eligible for a clinical trial, but decline participation, as it may affect the magnitude of an intervention, and ultimately its clinical meaningfulness. The RASTA cohort study will address this issue in patients with AF. Atrial fibrillation has become a significant burden globally, and is more often present in older individuals. This is particularly important in Nova Scotia where our healthcare system is especially burdened as the population ages, 20% of the current population is >65 years. Improved understanding of the AF patient population in Nova Scotia, and beyond, will permit further understanding of how best to treat this increasingly common chronic illness.

The RASTA-Cohort study is designed to answer the following questions:

• Do patients who decline participation in the RASTA AF RCT have different clinical characteristics and quality of life than patients who accept participation in the study.
• Do patients who do not participate in the RASTA AF RCT suffer from worse AF-related outcomes than patients in the study, as compared to the control arm and intervention arm.

This is a multicenter, prospective cohort study that will enrol patients who are eligible for, but do not participate in the RASTA-AF study, but agree to be followed in this registry. Once the patient has consented to participate in RASTA Cohort, they will be scheduled for their AF ablation at the next available timeframe (2-4 months from entry into the study). All patients will continue to receive care as per current guidelines; this will be managed at the discretion of their treating physician.

Clinical characteristics collected at baseline include quality of life (CCS-SAF, AFEQT, EQ-5D), physical activity measures: IPAQ and stress test results (where available), blood pressure, weight, hemoglobin A1C, alcohol use and smoking cessation. The measures of risk factors will be performed in a similar fashion as the main study to ensure that these can be compared.

The conservative estimated event rate for the cohort is 20% greater than that of the control population of the RASTA AF study. Given the control population having an event rate of 30%, and the cohort group being 43.5%, a sample size of 313 patients is required in the control population of RASTA and 185 patients in the cohort group with a minimum 2 year follow up. Using a 7% loss to follow up rate, the sample size required in the cohort group is 198 patients. This sample size will provide 90% power with a type I error of 0.05 to detect a difference in survival between the cohort and the control group in the study. There is >99% power to detect a difference between the intervention group and the cohort group based on the sample of 198 patients.

Inclusion criteria

• symptomatic AF (CCS-SAF ≥2),
• paroxysmal or persistent atrial fibrillation despite rate control, desiring catheter ablation and either: i) BMI ≥ 30 or, ii) at least two of the following: BMI>27, BP>140/90 mmHg or history of hypertension, Diabetes, Heart failure (prior heart failure admission or LVEF<40%), Age ≥ 65 years, Prior stroke/TIA, Current smoker, Excessive alcohol use {For women: 10 or more drinks/week, more than 2 drinks a day (most days). For men: 15 or more drinks/week, more than 3 drinks a day (most days)}, and iii) declined or were not approached for participation in the main study. Eligible patients must have received catheter ablation for AF during the same timeline of the RASTA-AF Mian Study (November 1st, 2019 to December 31st, 2025).

Exclusion criteria

• permanent AF (AF lasting > 3 years),
• prior catheter ablation for AF
• New York Heart Association Class IV heart failure
• participation in a cardiac rehabilitation program within the last year,
• currently performing exercise training >150 minutes/week of moderate to vigorous physical activity,
• unable to exercise,
• unable to give informed consent,
• other noncardiovascular medical condition making 1 year survival unlikely
• less than 18 years of age