Segurança e efetividade da estimulação elétrica definitiva do sistema de condução cardíaco

Abstract

Right ventricular pacing is an established therapy for the treatment of bradycardias and for cardiac resynchronization therapy (CRT). Frequent stimulation of the right ventricle, with a left bundle branch block pattern, can lead to pacing-induced cardiomyopathy (PICM). Conduction system pacing, either through direct His bundle pacing or the left bundle branch pacing, is associated with the prevention of PICM, as it provides a narrow paced QRS. It is also a promising therapy in patients with ventricular dysfunction, as an alternative to conventional CRT. The overall objective is to describe the safety and efficacy of conduction system pacing technique in a cohort of patients indicated for cardiac pacing, according to current guidelines. The specific objectives are: to describe the success rate in meeting the criteria for conduction system pacing, to describe the occurrence of complications related to this procedure, to describe the evolution of R wave amplitude and thresholds of the conduction system at the time of implantation and during clinical follow-up, and to describe the clinical-ecocardiographic evolution in patients with bundle branch block and systolic ventricular dysfunction. The methodology was a single-center, retrospective and prospective cohort study of consecutive patients who underwent conduction system pacing implantation from July 2017 to June 2024, with the collection of demographic, electrocardiographic, echocardiographic data, and device evaluation at implantation and during follow-up. As a result, 397 patients were analyzed with a mean age of 79.12 years, 267 male patients (64.74%). Conduction system pacing was successful in 98.5% of cases. There was a significant reduction in the duration of the QRS complex in the sample. Among the patients with heart failure, there was a significant increase in left ventricular ejection fraction (LVEF) (p<0.001) and a significant reduction in left ventricular diameters and volumes. Conclusion: The conduction system pacing technique was used safely and effectively in this sample. CIED implantation for conduction system pacing had a high success rate, comparable to conventional techniques. Patients undergoing conduction system pacing had low complication rates, consistent with those reported in the literature. conduction system pacing produced adequate capture and sensitivity thresholds at the time of implantation and which were maintained during follow-up. Patients undergoing conduction system pacing had narrower mean QRS complexes after implantation. The indication for conduction system pacing did not correlate with worsening of FC, mean LVEF, or increase in mean LV cavity diameters during the study observation period. In the subgroup of patients with LV dysfunction and bundle branch block, including those with indication for CRT, when undergoing conduction system pacing, there was a significant increase in mean ejection fraction and a significant reduction in mean LV end-systolic and diastolic volumes.