Is the rapidly paced pig the optimal model for endocardial cardiac resynchronization therapy? —Authors’ reply

We very much appreciate the insightful letter by Niedereret al.1 about our recent publication inEuropace.2 Most of the scientific evidence supporting the hypothetical superiority of left ventricular endocardial pacing comes from animal studies using canine models or simulation studies also based on this model.3 Unfortunately, these results have not been reproduced in clinical studies. The large multicentre prospective human trial ALternate Site Cardiac ReSYNChronization (ALSYNC), which included only patients who had failed or were unsuitable for conventional cardiac resynchronization therapy (CRT), showed that the rate of responders to endocardial pacing was similar to the rate of responders to classical CRT.4 Furthermore, a recent meta-analysis and systematic review of the literature reports not superior, but comparable, response rate of endocardial CRT vs. conventional epicardial CRT.5 We have developed a new swine model of heart failure and dyssynchrony. The results of our study using this model are in accordance with clinical studies. Our model has specific characteristics that mimic more accurately those of patients with advanced cardiomyopathy, thus explaining the results. First, studies in humans with heart failure and advanced myocardial disease have demonstrated damage of the distal Purkinje network and conduction remodelling.6 These changes result in slower conduction velocities at the level of the human diseased endocardium not much different to the conduction velo...

Source: Europace - October 12, 2017 Category: Cardiology Source Type: research