Mechanistic Cardiac Imaging of Conduction System Pacing: Deformation, Diastolic Function, and Substrate-specific Response

Conduction System Pacing (CSP), which includes His bundle pacing and left bundle branch area pacing (LBBAP), represents an evolving approach to reestablishing physiologic ventricular activation. Despite growing clinical use, there is an important disconnect between surface electrical indicators such as QRS narrowing and actual mechanical or functional improvement, particularly within the spectrum of cardiomyopathies. Underlying conditions such as myocardial scar, infiltration, inflammation, or hypertrophy frequently alter the relationship between ventricular depolarization, as captured on ECG, and the true mechanical contraction and filling of the left ventricle. As a result, patients with apparently similar paced QRS patterns may experience divergent outcomes in terms of left ventricular remodeling, strain patterns, and diastolic performance.This Research Topic aims to link CSP-induced electrical changes with rigorous cardiac imaging endpoints to refine the definition of “successful” conduction recruitment. It prioritizes studies that connect septal capture patterns, including nonselective conduction system pacing, left ventricular septal pacing (LVSP), and deep septal pacing (DSP), and criteria for LBBAP, to direct measurements of ventricular mechanics. By focusing on mechanistic echocardiography and/or cardiac MRI (CMR) outcomes, the Topic seeks to bridge clinical electrophysiology and advanced imaging. Studies must go beyond descriptive technique or outcome audits by directly measuring deformation, synchrony, efficiency, and diastolic function in response to various CSP strategies. Disease-specific experience is especially sought in challenging cardiomyopathies such as cardiac sarcoidosis, cardiac amyloidosis, and hypertrophic cardiomyopathy (HCM), but insights from other forms of cardiomyopathy are welcomed when anchored to mechanistic imaging analysis.This Research Topic explicitly requires that submissions employ mechanistic imaging endpoints (such as echocardiographic strain, tissue Doppler, myocardial work indices, CMR-derived metrics, or similar modalities) and/or imaging-anchored criteria for confirming conduction recruitment, rather than relying on QRS measurements or outcome data alone. Submissions that only report ECG/EGM or clinical outcomes without such mechanistic endpoints will be considered out of scope.To facilitate broad participation while maintaining thematic coherence, the following themes are central:• Comparative effects of nonselective CSP versus LVSP/DSP on LVEF, ventricular remodeling, and mechanical deformation (including strain and myocardial work);• Mechanisms and imaging correlates that define “successful” LBBAP beyond QRS narrowing, assessing their predictive value for mechanical resynchronization and diastolic function;• Disease phenotype–specific effects: how scar, infiltration, inflammation, or hypertrophy influence CSP response in sarcoid, amyloid, HCM, and complex cardiomyopathies such as NICM, ischemic cardiomyopathy with septal scar, pacing-induced or post-myocarditis cardiomyopathy;• The predictive value of imaging phenotypes (LGE, T1 mapping/ECV, LA strain, etc.) for identifying responders to CSP;• Mechanistic studies identifying links between improved conduction via CSP and diastolic function, including filling, relaxation, LA mechanics, and untwisting;• Temporal changes in mechanical and diastolic indices, acute versus chronic adaptation to CSP. Topic editors: Habib Khan, Mouhannad Sadek, Zachary Whinnett Source: https://www.frontiersin.org/research-topics/83699/mechanistic-cardiac-imaging-of-conduction-system-pacing-deformation-diastolic-function-and-substrate-specific-response