Acute hemodynamic effects of a novel algorithm for cardiac resynchronization therapy optimization: Results from the BIO|Adapt study

<h2>ABSTRACT</h2><h3>Background</h3> A considerable proportion of heart failure patients with reduced left ventricular ejection fraction (LVEF) and prolonged QRS duration fail to respond adequately to Cardiac resynchronization therapy (CRT). Suboptimal atrioventricular (AV) delay programming is a key factor leading to diminished response. <h3>Objective</h3> To acutely correlate aortic velocity time integral (AoVTI), LVEF, and QRS duration with three programming strategies in the post-implantation setting: AV delay automatically set by a novel CRT AutoAdapt algorithm, AV delay optimized by echocardiography, and standard (‘in-box') programming. <h3>Methods</h3> Under normal intrinsic AV conduction (<250 ms after atrial pacing), the CRT AutoAdapt algorithm automatically switches to left ventricular-only pacing and adapts the AV delay to 50%, 70% (default), or 90% of intrinsic AV conduction. In our study, 163 CRT-defibrillator recipients (mean age 69.2±9.2 years, 32% female; LVEF 27.7%±6.6%; 76% with left bundle branch block) underwent echocardiographic and electrocardiographic assessments at pre-hospital discharge. <h3>Results</h3> With the default 70% AV adaptation, the CRT AutoAdapt automatically set similar AV delay (117.1±23.9 ms) compared to echocardiography-guided optimization (118.3±30.2 ms, p=0.94). Strong concordance was observed between the algorithm and echocardiographic optimization for AoVTI (concordance correlation coefficient: 0.96) and LVEF (0.93). Both optimization methods significantly outperformed standard AV programming for LVEF improvement (p<0.001) and QRS width reduction (p<0.01), with no significant differences between optimization approaches. <h3>Conclusion</h3> Acute hemodynamic effects of CRT AutoAdapt and echocardiographic AV delay optimization were similar, with equivalent cardiac performance. This device-based approach offers the potential advantage of continuous adaptation to changing physiological conditions without requiring resource-intensive in-office optimization procedures.