For a substantial number of patients who develop atrial fibrillation, normal sinus rhythm cannot be restored and maintained with standard drug therapy, including newer agents such as amiodarone or sotalol. While many patients can hemodynamically tolerate chronic atrial fibrillation, those with rapid ventricular response rates or underlying systolic dysfunction can have serious deterioration in cardiac function. Ablation of the atrioventricular node with implantation of a permanent pacemaker is an alternative method for treatment of symptomatic atrial fibrillation in refractory patients. Ozcan and colleagues report on a comparison of long-term survival in patients with atrial fibrillation treated with drug therapy or node ablation/pacemaker.
A total of 350 patients from the Mayo Clinic who underwent radio frequency node ablation/pacemaker implantation (hereafter referred to as surgical treatment) from 1990 to 1998 were compared with 229 control subjects who received drug therapy for atrial fibrillation. Both groups were measured against the survival rate for the age-matched general Minnesota population.
Complete heart block was successfully induced in all node-ablated patients. An additional left-sided catheter approach during the initial procedure was needed in 2 percent of ablated patients, and a second or third procedure was required in 7 percent of patients to achieve successful heart block. After surgical treatment, one or more cardiac drugs were still necessary in 54 percent of patients because of other underlying cardiac disease.
Medical and surgical treatments of atrial fibrillation were shown to have statistically equivalent long-term survival rates. Both therapies were associated with worse survival than that in the age-matched general population. Subgroup analyses of patients with congestive heart failure or coronary artery disease also showed equivalent survival rates. Independent predictors of reduced survival included a previous history of congestive heart failure, myocardial infarction or continued need for cardiac drugs after surgical treatment. Patients with none of these predictors had a survival rate equal to that of the general population after surgical therapy of atrial fibrillation.
The authors conclude that the long-term safety of node ablation/pacemaker treatment for atrial fibrillation is confirmed by an equivalent survival rate when compared to drug therapy.
editor's note: While the authors helpfully demonstrate there are no long-term problems with node ablation/pacemaker treatment versus drug therapy, I believe most physicians are curious about whether there are any advantages to this approach. The only subgroup that did better than the usual drug treatment of atrial fibrillation was those patients without previous myocardial infarction or a continued need for cardiac drugs after surgical therapy. Perhaps in this subgroup there may be a convenience and survival advantage to node ablation/pacemaker implantation.—b.z.