Abstract 18556: Renal Sympathetic Denervation Modulates Cardiac Repolarization in a Post Myocardial Infarction Pig Model

Abstract

Introduction: Changes in cardiac repolarization parameters such as QT interval and QT dispersion have been implicated in cardiac arrhythmogenesis following acute myocardial infarction (AMI). These parameters are susceptible to sympathetic modulation. We therefore hypothesized that renal sympathetic denervation (RDN) may produce potential anti-arrhythmic actions through its effects on cardiac repolarization. Methods: Fifteen pigs randomized to AMI & RDN (6 pigs), AMI & sham RDN (6 pigs) and sham MI & sham RDN (3 pigs) underwent percutaneous occlusion of the mid to distal LAD to achieve AMI. 2 weeks after infarction, the St. Jude EnligHTN® basket catheter was used to perform RDN bilaterally. Cardiac repolarization parameters were measured at 3 time points over the course of the 3 week study: baseline (immediately before MI), midpoint (2 weeks post MI; at time of RDN) and end (1 week post RDN). ECG data were acquired from limb leads. Results: In a ten beat span, the range in the durations of the QT interval was seen to increase from 18+/-7ms to 19+/-11ms in the real AMI & sham RDN group while in the real AMI & real RDN group it decreased from 17+/-5ms to 14+/-5ms (p=0.11). The mean QT interval which increased by 25% in the real AMI & sham RDN group saw only an 11% increase in the real AMI & real RDN group (p=0.048). The standard deviation of the average QT intervals post AMI, which quantifies the reduction in global dispersion of repolarization, saw a 41% decrease with RDN compared to an 8% decrease with sham RDN. The temporal dispersion of repolarization was also diminished by RDN. The dispersion of T wave peak to T wave end durations which increased in the real AMI & sham RDN group (from 15+/-6ms to 22+/-10ms), was decreased in the real AMI & real RDN group (from 19+/-7ms to 16+/-6ms) (p=0.05). T wave alternans values displayed no significant response to RDN (p=0.977). Conclusions: Adverse changes in cardiac repolarization parameters were attenuated via renal denervation in this post infarct pig model. These effects may mitigate post infarct arrhythmogenesis but require further study to evaluate the influence of local, reflex and circulating mediators.