Introduction
Cardiac resynchronization therapy (CRT) has been shown to prevent
hospitalizations for heart failure and improve mortality in patients
with severe left ventricular (LV) dysfunction and inter-ventricular or
intra-ventricular electromechanical dyssynchrony (1-8). However, LV lead
placement (LV-LP) in the target branch of the coronary sinus (CS)
tributaries can be difficult due to variations in coronary venous
anatomy (9) despite the recent advances in delivery systems for LV-LP
(10-14).This is one of the causes of non-response to CRT. In general,
9Fr or 10Fr outer guiding catheters (Outer-Cath) with a variety of
curves and shapes are initially selected for CS cannulation to serve as
backup force for LV lead delivery to a target vein. At other times, a
subselection inner catheter (Inner-Cath) may be used adjunctively to
guide the Outer-Cath into the CS more safely, especially in difficult
cases of CS cannulations, which can lead to complications such as CS
dissection or perforation (15, 16). However, efficacy and safety of the
LV-LP using only the smaller 7Fr Inner-Cath for CRT implantation has
never been investigated before. The aim of this study was to investigate
the feasibility, efficacy, and safety of LV-LP guided only by an
Inner-Cath as a first-line approach to CRT implantation.