Super-response to cardiac resynchronization therapy may predict late phrenic nerve stimulation

Area of Science:

• Cardiology
• Medical Devices
• Electrophysiology

Background:

• Cardiac resynchronization therapy (CRT) can cause reverse remodeling in super-responders.
• This remodeling may alter the anatomical relationship between the left phrenic nerve and coronary veins.
• This anatomical shift is a potential cause of late-onset phrenic nerve stimulation (PNS) without lead dislodgement (LD).

Purpose of the Study:

• To investigate if super-response (SR) to CRT predicts late-onset PNS.
• To evaluate the association between SR and non-lead dislodgement related PNS (non-LD-PNS).

Main Methods:

• Retrospective analysis of patients with CRT and LV leads.
• Classification of PNS as early (<3 months) or late (>3 months).
• Definition of LD-PNS based on lead threshold/impedance changes or displacement; non-LD-PNS otherwise.
• SR defined as ≥30% reduction in left ventricular end-systolic volume at 1-year follow-up.

Main Results:

• PNS occurred in 20 of 139 patients over a mean follow-up of 32 months.
• Late non-LD-PNS incidence was significantly higher in the SR group (13.1%) compared to the non-SR group (1.3%).
• Super-response was the sole predictor of non-LD-PNS in multivariate analysis (OR: 11.62, P=0.023).

Conclusions:

• Late non-LD-PNS is more frequent in super-responders to CRT.
• This finding supports the hypothesis that anatomical changes in the phrenic nerve and coronary veins contribute to late-onset PNS in SR patients.