Weight management and Atrial Fibrillation: The impact of weight and risk factor management on AF burden in overweight and obese patients.

INTERVENTION: The Weight Management and Atrial Fibrillation is a multi‐component prospective study aimed at investigating multiple research questions pertinent to obesity and atrial fibrillation: 1. The impact of weight and risk factor management on AF burden in overweight and obese patients 2. The impact of weight reduction prior to AF catheter ablation on procedure outcomes, in overweight and obese patients 3. The impact of weight reduction on the AF substrate and autonomic system modulation in overweight and obese patients: A mechanistic study (separate registration) Weight Management and Atrial Fibrillation: The impact of weight and risk factor management on AF burden in overweight and obese patients. Patients in the intervention group undergo a 2 phase physician‐led weight management program concurrently with tight metabolic risk factor control. Upon randomization to the intervention arm, patients undergo a 2 month modified very low calorie diet (VLCD) and a gradually titrated low intensity exercise program. During the high intensity modified VLCD phase, patients will be prescribed a standard nutritionally complete meal replacement product (Prima Health Solutions, Kickstart) for 2 of the 3 daily meals. This will be ongoing for 2 months and used in conjunction with a didactic eating plan framework. Generally, patients will be prescribed an eating plan focusing on: 1. Calorie maintenance 800‐1200 calories/day 2. Low glycemic index foods 3. High mono and poly unsaturated fats based foods 4. Low saturated fats, cholesterol and sodium based foods 5. Alcohol reduction (less than or equal to 30g/week) Patients will be required to maintain a lifestyle journal outlining: 1. Exercise (duration and type) 2. Food intake (quantity and type) 3. Blood pressure measurements Physical activity prescription is tailored as follows: 1. Initially 3 x 20 minute sessions of low intensity exercise per week (usually walking) 2. This is titrated upwards over the initial 2 months to 1 – 2 low intensity session(s) plus 1 – 2 moderate intensity session(s) per week. Moderate intensity sessions include, jogging, brisk walking, swimming, cross‐trainer, rowing machine, cycling 3. In the case of limiting musculoskeletal conditions, hydrotherapy or aqua aerobics are utilized instead 4. Patients are encouraged to utilize pedometers to quantify their personal best and to aim to supersede this over time At commencement, they are issued with pre‐specified written material on healthy eating, dining out, food shopping and physical activity. During the initial phase of the program, patients will be reviewed monthly in a specialized weight and risk factor management clinic along with their lifestyle journal. Following the 2 month high intensity phase, patients will undergo a more gradual weight management program with greater focus on permanent lifestyle change. During the second phase of the study, meal replacement sachets will be discontinued. Patients will be reviewed 3 monthly in the clinic for the remaining duration of follow‐up (15‐months). At baseline, weight, body mass index (BMI), waist circumference (WC), height, blood pressure as well as baseline demographic data are recorded. Patients have blood drawn for baseline fasting biochemistry (BUN, LFTs, INR, hsCRP, TSH, T4, Insulin, Glucose, Cholesterol, HDL, LDL and triglycerides). All patients undergo stringent risk factor identification and management. In addition to weight, metabolic risk factors include: 1. Smoking 2. Hyperlipidemia 3. Hypertension 4. Glucose intolerance or diabetes mellitus 5. Alcohol intake 6. Obstructive sleep apnea CONDITION: Atrial arrhythmias Obesity INCLUSION CRITERIA: Inclusion criteria were: symptomatic paroxysmal or persistent AF; BMI (kgm‐1)>27; waist circumference (cm) >100 (male) or >90 (females); and age 21‐75 years. All patients undergo sleep apnea screening through overnight polysommnography at a dedicated sleep unit. When clinically indicated (in conjunction with AHI interpretation), CPAP may be prescribed and titrated. Patients are educated about tobacco and alcohol harm and provided with written education. Follow‐up and feedback is provided on clinic visits. Alcohol reduction to less than or equal to 30g/week is aimed for, in view of established metabolic disease and cardiac arrhythmia. In the event of intermediate fasting glycemia, a 2 hour glucose tolerance test is undertaken. If glucose intolerant or insulin resistant continued lifestyle measures are pursued. Patients with frank diabetes are prescribed oral hypoglycemic agents and referred to a diabetes clinic. Hypertension is diagnosed based on family physician records and documented readings in the lifestyle journal. Management with a combination of lifestyle measures, salt reduction and pharmacotherapy is undertaken. Medication may be combined and titrated based on clinician judgment and patient tolerance. During the follow‐up visits, patients will undergo face‐to‐face counseling and feedback based on anthropometric measures and lifestyle journal. Patients will have access to 24 hour email and telephone support in addition to additional counseling sessions if required. At each ap PRIMARY OUTCOME: Atrial arrhythmia burden and freedom from atrial fibrillation. Requirement for an ablation procedure or relapse into AF following an ablation. This is done using validated AF‐specific questonnaires, Holter monitoring and 12 lead‐ electrocardiograph (ECG) recordings. Cardiac structure and function on echocardiography and doppler echocardiography. SECONDARY OUTCOME: Atrial ectopy burden. This will be assessed by continuous 7‐day Holter monitoring. Cardiac structure and function. Delayed‐enhancement atrial scar burden. This will be performed using cardiac magnetic resonance imaging (CMR) with delayed contrast enhancement. Non‐invasive and invasive assessment of the atrial arrhythmic substrate. Atrial voltage maps and conduction velocity. Serum fasting biochemistry