F-18 fluorodeoxyglucose imaging to differentiate the response to cardiac conduction system pacing in patients with pacing induced cardiomyopathy

Pacing-induced cardiomyopathy (PICM) results from the detrimental effect of frequent right ventricular pacing. [1]The diagnosis relies on a combination of pacing-associated ventricular dyschrony manifested with ECG wide LBBB-pattern QRS duration and clinical assessment, imaging studies.Conduction system pacing (CSP), such as His bundle pacing (HBP) and left bundle branch pacing (LBBP), may help to prevent PICM, [2] but the criteria for optimal patient selection remain inadequately defined.Recent study demonstrated that left bundle branch pacing (LBBP) improves left ventricular (LV) function in patients with PICM by restoring physiological activation propagation in the left ventricle. [3]However, it is important to note that some patients may not well respond to LBBP.The etiology of varied responses to LBBP in patients with PICM remains poorly understood, and reliable predictive models for these differential outcomes are currently lacking.FDG imaging serves as a valuable tool for estimating the energetic metabolism of myocardial cells that is relevant to cardiac mechanical work, while may yield the value in understanding the mechanism of cardiac response to pacing therapy.Hereinwe present two PICM patients underwent LBBP upgrades with significant postoperative electrocardiographic improvement, yet exhibited different 18 F-FDG imaging characteristics and follow-up outcomes.