Becoming Wiser with WiSE-CRT

Cardiac resynchronization therapy (CRT) is an important therapy for patients with heart failure and left bundle branch block. It aims to preexcite the late activated left ventricle (LV) and restore synchronized contraction. Trials consistently report successful suppression of heart failure and improved survival. However, there is a spectrum of effects such that some individuals may gain no benefit or even worsen. 1 Varma N. Boehmer J. Bhargava K. et al. Evaluation, management, and outcomes of patients poorly responsive to cardiac resynchronization device therapy. J Am Coll Cardiol. 2019; 74: 2588-2603 Crossref PubMed Scopus (48) Google Scholar Insufficient electrical preexcitation may contribute to this heterogeneity. Variations in coronary sinus anatomy may prevent lead delivery to the site of latest activation. A fundamental limitation of traditional CRT is that wavefront propagation after LV epicardial pacing is slow, even in the normal myocardium. 2 Wiggers C.J. The muscular reactions of the mammalian ventricles to artificial surface stimuli. Am J Physiol. 1925; 73: 346-378 Crossref Google Scholar This may become limiting when there is LV enlargement. Wavefront propagation may be further impeded by conduction barriers (scar-related or functional). 3 Wisnoskey B.J. Varma N. Left ventricular paced activation in cardiac resynchronization therapy patients with left bundle branch block and relationship to its electrical substrate. Heart Rhythm O2. 2020; 1: 85-95 Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar In contrast, LV endocardial pacing generates rapidly propagating wavefronts. 4 Myerburg R.J. Gelband H. Nilsson K. Castellanos A. Morales A.R. Bassett A.L. The role of canine superficial ventricular muscle fibers in endocardial impulse distribution. Circ Res. 1978; 42: 27-35 Crossref PubMed Scopus (52) Google Scholar Transvenous leads may be delivered transseptally to the LV endocardium but introduce vulnerability to chronic thromboembolic complications despite long-term anticoagulation. 5 Morgan J.M. Biffi M. Geller L. et al. ALternate Site Cardiac ResYNChronization (ALSYNC): a prospective and multicentre study of left ventricular endocardial pacing for cardiac resynchronization therapy. Eur Heart J. 2016; 37: 2118-2127 Crossref PubMed Scopus (115) Google Scholar This limitation is overcome by leadless LV endocardial pacing. Guided implantation of a leadless left ventricular endocardial electrode and acoustic transmitter using computed tomography anatomy, dynamic perfusion and mechanics, and predicted activation patternHeart RhythmPreviewThe WiSE-CRT System (EBR systems, Sunnyvale, CA) permits leadless left ventricular pacing. Currently, no intraprocedural guidance is used to target optimal electrode placement while simultaneously guiding acoustic transmitter placement in close proximity to the electrode to ensure adequate power delivery. Full-Text PDF Open Access