Permanent His-Bundle Pacing After Atrioventricular Node Ablation in a Patient With Chronic Atrial Fibrillation and Mitral Regurgitation

Effect of pacing method on risk of sudden death after atrioventricular node ablation and pacemaker implantation in patients with atrial fibrillation

BACKGROUND

Sudden death may occur after radiofrequency catheter ablation of the atrioventricular node (AVN) and permanent pacemaker implantation. It is unclear whether a faster initial heart rate with gradual rate reduction decreases the risk of sudden death.

OBJECTIVE

To evaluate the effects of initial pacing at a faster rate after AVN ablation, with a gradual rate decrease over 3 months, on the rate of sudden death in patients with atrial fibrillation.

METHODS

We compared the rate of likely or possible procedure-related sudden death in 2 groups of patients who had AVN ablation and pacemaker implantation. The study cohort was treated between January 2005 and December 2009, and pacemakers were programmed to a lower rate of 90 beats/min after the procedure, with a monthly decrement of 10 beats/min until 60 beats/min was reached. The control group was treated between July 1990 and December 1998 when pacemakers were programmed to a lower rate of 60 beats/min immediately after ablation.

RESULTS

The study cohort included 520 patients (mean age 73.6 ± 10.3 years), and the control cohort comprised 334 patients (mean age 68.1 ± 1.1 years). Sudden death deemed likely or possibly related to ablation and pacemaker implantation occurred in 1 patient in the study cohort (0.2%) and in 7 patients (2.1%) in the control group (P = .007).

CONCLUSIONS

Sudden death was significantly decreased in the study cohort compared to controls. The faster lower pacing rate immediately after AVN ablation with a gradual decrease is a plausible mechanism for the improved clinical outcome.

Biventricular pacing in paced patients with normal hearts

Right ventricular apical (RVA) stimulation, although beneficial in the treatment of symptomatic bradycardia, has proven detrimental in a substantial percentage of pacemaker recipients, leading to iatrogenic deterioration of left ventricular structure and function. Alternative right ventricular pacing sites appeared advantageous but their superiority has not been proven. Biventricular stimulation is effective in reducing ventricular dyssynchrony in subgroups of heart failure patients, improving their functional capacity, morbidity, and mortality. Therefore, it seems logical that this pacing strategy, by eliminating ventricular dyssynchrony, could play an important role in preventing the deleterious effects of chronic RVA stimulation in patients with normal hearts who undergo cardiac pacing for bradycardia indications. Preliminary investigations have yielded encouraging results, but further studies with harder endpoints such as quality of life, morbidity, and mortality are necessary to clarify the potentially advantageous effect of biventricular stimulation in paced patients with normal hearts.

Randomized Comparison of Bipolar vs Unipolar Plus Bipolar Recordings During Atrioventricular Junction Ablation Importance and Efficacy of Unipolar Recording

BACKGROUND

No prior studies have clarified the utility and efficacy of unipolar recording for identifying successful sites for atrioventricular junction (AVJ) ablation.

METHODS AND RESULTS

Thirty-six patients underwent radiofrequency (RF) AVJ ablation for drug-resistant atrial fibrillation (AF) or AF/flutter. AVJ ablation was performed with either bipolar (Bi-group; n=18) or unipolar plus bipolar recording (Uni-group; n=18). In the Uni-group, the primary parameter used to select ablation sites was a QS or rS morphology of the His bundle unipolar recording. There was no significant difference between the 2 groups for the bipolar electrogram characteristics at the successful ablation site. However, in the Uni-group, the procedure time and fluoroscopy duration were shorter (both p<0.05), and the total number of RF energy applications less (p<0.05) than in the Bi-group. In the Uni-group, unipolar His bundle recordings could be assessed in 26 (76%) of 34 RF energy applications: Complete atrioventricular block was obtained at 15 (83%) of 18 sites with QS morphology and in 3 (37%) of 8 sites with rS morphology on the unipolar His bundle recording.

CONCLUSIONS

AVJ ablation can be achieved more efficiently and with fewer RF energy applications when guided by unipolar recordings than by bipolar recordings alone.