Background:
Cardiac resynchronization therapy (CRT) decreases mortality, reduces heart failure hospitalizations, and improves quality of life.1-7 Conventionally the left ventricular (LV) lead is placed via the coronary sinus (CS). However, frequently encountered problems during CS lead placement include anatomic and technical difficulties, such as inability to cannulate the CS, limited lateral or posterolateral branches, venous occlusion, extracardiac stimulation, or high pacing thresholds.8 Additionally, there are a significant number of patients that do not clinically benefit from CRT, as high as 20-40% in some series.7
Given these issues, alternative pacing sites have been described including the His bundle, left bundle branch, surgical epicardial, as well as LV endocardial locations. Conduction system pacing is not possible in every patient, epicardial leads are higher risk given the requirement for surgical placement while LV endocardial leads carry an increased risk of ischemic stroke.9-15
Despite the risks, LV endocardial pacing does offer several advantages including access to the entire LV for lead placement and impulse propagation starting in the endocardium allowing for more physiologic depolarization.16-19
The current practice of CS or His bundle lead placement are preferable due to their minimal risk of implantation, negligible stroke risk, and reduced bleeding risk given that long-term anticoagulation is not required. This case series, however, highlights the continued need for alternative approaches and describes a viable option for scenarios in which the current standard practice is not feasible.