Treatment of patients with symptomatic atrial fibrillation (AF) for whom antiarrhythmic drug therapy and/or pulmonary vein isolation procedures are either inappropriate or ineffective centers around relieving symptoms and controlling rate to prevent the development of tachycardia-induced left ventricular dysfunction. Rate control can often be achieved with the use of atrioventricular nodal blocking drugs such as β-blockers and calcium channel blockers.
In some patients, adequate rate control cannot be achieved even with high-dose combination regimens, medications are not tolerated, or adequate rate control results in symptomatic bradycardia. Some patients are uncomfortable with the irregularity even when ventricular rates are ideal. Atrioventricular node ablation and pacemaker placement have long been treatment considerations for these individuals.
The aging of the population and the increasing prevalence of AF in the elderly population has complicated the overall approach to treatment in the elderly population. Comorbid conditions and polypharmacy in these patients often limit therapeutic options. Successful rhythm control does not obviate the risk of stroke.
The cost to the health care system is considerable and growing. While national efforts are under way to reduce known risk factors for the development of AF, optimal management of this medically complex population is not yet clear. Whether there are specific, identifiable subsets that derive clear benefit from any particular strategy also is not apparent.
Win-Kuang Shen, M.D., is principal investigator in the Pacing and AV Node Ablation Compared to Drug Therapy in Symptomatic Elderly Patients With Atrial Fibrillation Clinical Trial (PACIFIC). This national clinical trial will explore approaches to treatment of AF in the elderly population. Specifically, this trial will compare atrioventricular node ablation and pacemaker implantation with pharmacologic rhythm or rate control. End points include all-cause mortality, cardiovascular hospitalization, quality of life, and overall resource utilization.
Other questions being addressed by Dr. Shen's clinical research program include optimal pacing modes, specifically right ventricular apical pacing vs cardiac resynchronization therapy (CRT), in elderly patients with AF receiving device treatment. Limited data thus far suggest that CRT improves left ventricular ejection fraction and reduces all-cause mortality, but large-scale randomized studies are needed to identify patients who will benefit from more aggressive CRT.