Rate Control in Atrial Fibrillation: Methods for Assessment, Targets for Ventricular Rate during AF, and Clinical Relevance for Device Therapy

Abstract

Rate control is a widely used treatment strategy for management of patients with atrial fibrillation (AF). Multiple studies have shown that pharmacologic rate control is as effective as pharmacologic rhythm control for management of AF. A snapshot ECG or intermittent monitoring using Holters is the most widely used technique for assessing ventricular rate during AF. Patients with implantable devices, such as pacemakers, implantable cardioverter defibrillators, cardiac resynchronization therapy devices, and implantable loop recorders provide the ability for continuous long term monitoring of AF and ventricular rate during AF. It has been shown that continuous monitoring of AF and ventricular rate during AF by implantable devices is the most comprehensive method for assessment of AF occurrence and poor rate control, particularly in patients with paroxysmal and asymptomatic AF. Rapid ventricular rate during AF, as assessed by implantable devices, has been shown to cause reduction in cardiac resynchronization therapy, predict inappropriate defibrillation therapy, and identify increased risk for cardiovascular hospitalizations. The ventricular rate targets for achieving good rate control during AF depend on the patient characteristics with stricter targets recommended for patient with compromised functional capacity, such as patients with HF. Thus it can be hypothesized that timely intervention based on continuous assessment of AF and poor rate control, with ventricular rate targets defined based on cardiovascular disease state, may improve clinical outcomes in patients with AF.

Figure 1.. Example showing the atrial fibrillation diagnostics measured in ICD devices. This patient had cardiovascular hospitalization and emergency department visits after long duration episodes of poor rate control during AF. The patient also had multiple days with defibrillator therapy on days with rapid ventricular rate during AF.

Figure:2. Atrial Fibrillation and poor rate control as detected by an implantable loop recorder.This patient was admitted multiple times with HF symptoms of shortness of breath and edema and was found to have AF with rapid ventricular rate on presentation. The patient had to be treated with IV diuretics during both admissions.

Figure: 3. Prolonged period of loss of cardiac resynchronization therapy pacing due to poor rate control during atrial fibrillation as documented by diagnostics provided in CRT-D devices.