Risk of Pacing-Induced Cardiomyopathy in Patients with High-Degree Atrioventricular Block-Impact of Right Ventricular Lead Position Confirmed by Computed Tomography

Prospective studies applying fluoroscopy for assessment of right ventricular (RV) lead position have failed to show clear benefits from RV septal pacing. We investigated the impact of different RV lead positions verified by computed tomography (CT) on the risk of pacing-induced cardiomyopathy (PICM). We retrospectively included 153 patients who underwent routine fluoroscopy-guided pacemaker implantation between March 2012 and May 2020. All patients had normal pre-implant left ventricular ejection fraction (LVEF). Patients attended a follow-up visit including contrast-enhanced cardiac CT and transthoracic echocardiography. Patients were classified as septal or non-septal based on CT analysis. The primary endpoint was PICM (LVEF < 50% with ≥10% decrease after implantation). Based on CT, 48 (31.4%) leads were septal and 105 (68.6%) were non-septal. Over a median follow-up of 3.1 years, 16 patients (33.3%) in the septal group developed PICM compared to 31 (29.5%) in the non-septal group (p = 0.6). Overall, 13.1% deteriorated to LVEF ≤ 40%, 5.9% were upgraded to cardiac resynchronization therapy device, and 14.4% developed new-onset atrial fibrillation, with no significant differences between the groups. This study demonstrated a high risk of PICM despite normal pre-implant left ventricular systolic function with no significant difference between CT-verified RV septal or non-septal lead position.

Bradyarrhythmias and Physiologic Pacing in the ICU

Bradyarrhythmias represent a common pathology in the intensive care unit (ICU) with etiologies of varying severity. Treatment has often been focused on correcting underlying causes and may require pacing for urgent hemodynamic support. In recent years, there has been interest in physiologic pacing modalities which avoid the dyssynchrony from right ventricular (RV) only pacing. Cardiac resynchronization therapy (CRT) through biventricular pacing is a well-established device-based electrical therapy in patients with wide QRS and heart failure. Recently, it has been shown that biventricular pacing may also be pursued for hemodynamic rescue in the ICU setting. Efforts to re-engage the conduction system with His bundle pacing or further downstream have also emerged as alternative means to deliver resynchronization, with early applications in the ICU now being reported. The goal of the review is to examine bradyarrhythmia causes and management in the ICU as well as investigate new approaches in physiologic pacing and their potential roles in critically ill patients.