Heightened risk of intensive rate control in patients with atrial fibrillation who are obese or have type 2 diabetes: A critical review and re‐evaluation

Atrial fibrillation (AF) is common in patients with obesity and diabetes; the arrhythmia (if long-standing) is typically managed by rate control and anticoagulation. However, the coexistence of these two metabolic disorders complicates therapeutic options for rate control. The likely pathogenesis of AF in these patients is an expansion of epicardial adipose tissue whose inflammation is transmitted to the left atrium causing electromechanical remodeling. However, this same process is also transmitted to the left ventricle (LV), impairing its distensibility and its ability to tolerate volume, leading to heart failure with preserved ejection fraction. Unfortunately, the latter diagnosis (although commonly present in patients with AF and a coexistent metabolic disorder) is often ignored. To achieve rate control, physicians prescribe intensive treatment with atrioventricular (AV) nodal-blocking drugs, often at doses that are titrated to blunt exercise as well as resting heart rate responses. However, strict rate control (target rate, <80/min) is associated with somewhat worse outcomes than lenient rate control (target rate, <110/min). Furthermore, any rate slowing that facilitates diastolic filling may aggravate filling pressures that are already disproportionately increased because the LV is stiff and overfilled as a result of cardiac inflammation. Rate slowing in AF with beta blockers may not achieve the benefit expected from the blockade of adrenergically mediated cardiotoxicity, and some AV nodal-blocking drugs (digoxin and dronedarone) can increase the risk of death in patients with AF. Finally, cardiac fibrosis in obesity and diabetes may affect the conduction system, which can predispose to serious bradyarrhythmias if patients are prescribed AV nodal-blocking drugs.