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.