Is the rapidly paced pig the optimal model for endocardial cardiac resynchronization therapy?

Current endocardial cardiac resynchronization therapy (CRT) is performed predominantly in non-responders to CRT.1 Previous clinical,2 pre-clinical,3 and simulation4 comparisons found endocardial CRT offered a more physiological and rapid activation pattern to epicardial CRT. In contrast the study by Amor ós-Figueraset al.5 found endocardial pacing induced similar haemodynamic changes to epicardial pacing in a porcine animal model of right ventricular (RV) pacing induced non-ischaemic cardiomyopathy. While these results are interesting, highlighting the need to identify the optimal pacing site for both epicardial and endocardial CRT, the choice of animal and disease model may limit clinical translation. Specifically, the study was performed in pigs without left branch bundle block, as found clinically or in canine studies where the Purkinje network is ablated. The resulting cardiomyopathy confounds both rapid pacing induced and dyssynchronous heart failure making it a distinct pathological model from the conventional clinical case. The degree of wave-front fusion may also confound results. Pigs have a short PR interval (50 –120 ms),6 close to the atrioventricular (AV) delay (80/110  ms) used in the study thus slow trans-septal conduction may produce significant left ventricular activation through the intact Purkinje network. Porcine models have not been used to study CRT previously partly due to differences in Purkinje network compared with humans. The finding of no-dif...
Source: Europace - Category: Cardiology Source Type: research