Conduction system pacing improved pacing-induced cardiomyopathy in paediatric and young adult patients with congenital heart disease

Background Pacing-induced cardiomyopathy (PIC) occurs in approximately 10% of paediatric patients undergoing chronic right ventricular (RV) pacing for complete atrioventricular block (CAVB). Conduction system pacing (CSP) seems effective in preserving left ventricular (LV) function. Moreover, CSP was shown to be effective in adults with congenital heart disease (CHD) and PIC. Purpose Aim of this study was to assess the efficacy and safety of CSP in young patients with CAVB and PIC. Methods Paediatric patients with CAVB and PICM, with or without CHD, underwent transvenous implantation of a new system or upgrading of a prior system, pacing the proximal RV septum (RVS) close to right bundle branch or deep septum/left bundle branch area (LBBAP). Electromechanical function (QRS duration, ejection fraction, EF, and global longitudinal strain, GLS) was assessed at baseline, 1 month and 1 year after implantation in all patients. Data are reported as median (25th-75th percentile) and were compared with Kruskall-Wallis test. P<0.05 was significant. Results Ten consecutive patients (4 females) underwent new endocardial pacing system implantation (four) or upgrading of a prior endocardial system (six). Six patients had other CHD after surgical repair, four had isolated CAVB. CAVB was congenital in 6 patients, postoperative in 4 CHD. At baseline, age and weight were 22 (16-30) years (full range 7-46) and 52 (37-66) kg; QRS duration 165 (160-192); EF 45 (38-47)%, GLS -16 (-10-17)%. Four patients underwent pacing in proximal RVS (with stylet-driven leads), two deep septum pacing and four LBBAP (all lumenless leads). No complications occurred at implantation and during 1-year follow-up. QRS decreased to 124 (119-43) ms (P=0.0009) (Figure 1), EF increased to 54 (45-57) (1 month) (P=0.02) (Figure 2) and 52 (47-56) (1 year) (P=0.5); GLS did not increase significantly, -18 (-22-15) (1 month) (P=0.1) and -17 (-11-22) (1 year) (P=0.6). Conclusions In a small cohort of paediatric patients with PIC, CSP or pacing close to conduction system significantly decreased QRS duration and improved EF at 1-year follow-up, without procedure-related complications. GLS improvement was not significant.