Decreased postoperative atrial fibrillation following cardiac transplantation: the significance of autonomic denervation.

BACKGROUND: Endocardial ablation approaches targeting the retroatrial cardiac ganglia to treat atrial fibrillation (AF) have been proposed. However, the potential value using this approach is unknown. Disruption of the autonomic inputs with orthotropic heart transplant (OHT) provides a unique opportunity to study the effects of autonomic innervation on AF genesis and maintenance. We hypothesized that due to denervation, the risk of postoperative AF would be lower following OHT compared to surgical maze even though both groups get isolation of the pulmonary veins. METHODS AND RESULTS: We reviewed 155 OHTs (mean age 52 ± 11 years, 72% males) and used 1:1 age-, sex-, and date-of-surgery-matched two control groups from patients undergoing surgical maze or only coronary artery bypass grafting (CABG). Using conditional logistic regression we compared the odds of AF within 2 weeks following OHT versus controls. Postoperative AF occurred in 10/155 (6.5%) OHT patients. The conditional odds of postoperative AF were lower for OHT as compared to controls (vs maze: odds ratio [OR] 0.27 [95% confidence interval (CI) 0.13-0.57], vs CABG: OR 0.38 [0.17-0.81], P = 0.003; and on additional adjustment for left atrial enlargement, vs maze: OR 0.28 [0.13-0.60], vs CABG: OR 0.14 [0.04-0.47], P = 0.0009). CONCLUSIONS: Risk of postoperative AF is significantly lower with OHT as in comparison to surgical maze. As both surgeries entail isolation of the pulmonary veins but only OHT causes disruption of autonomic innervation, this observation supports a mechanistic role of autonomic nervous system in AF. The benefit of targeting the cardiac autonomic system to treat AF needs further investigation.

Baroreceptor-related dysrhythmias in piglets with selective autonomic denervation of the heart.

This study was carried out to determine whether selective cardiac autonomic denervation performed on neonatal swine would evoke dysrhythmias later in development. Piglets (n = 27; 5-10 days old) underwent unilateral stellate ganglion ablation, or right cardiac vagotomy, or sham surgery. Fifty to sixty days after denervation, acute experiments were performed to evaluate responses to baroreceptor activation. Of all animals who exhibited prolonged R-R intervals, only those with right stellate ganglion ablation had prolonged corrected QT intervals. Despite findings suggesting an arrhythmogenic state (predominance of left-sided cardiac innervation), dysrhythmias occurred in all animals with stellate ganglion ablation, regardless of laterality, but in few vagotomized or control animals. Our results suggest that partial sympathetic innervation may alter cardiac function so that dysrhythmias are more likely to occur during baroreceptor activation.