Author + information
- Received December 21, 2015
- Revision received March 31, 2016
- Accepted April 7, 2016
- Published online December 1, 2016.
- Jonathan M. Behar, MBBS, BSc∗ (, )
- Tom Jackson, MBBS,
- Eoin Hyde, PhD,
- Simon Claridge, LLB, MBBS,
- Jaswinder Gill, MD,
- Julian Bostock, PhD,
- Manav Sohal, MBBS,
- Bradley Porter, MBBS,
- Mark O'Neill, MD, DPhil,
- Reza Razavi, MD,
- Steve Niederer, DPhil and
- Christopher Aldo Rinaldi, MD
- Department of Imaging Sciences and Biomedical Engineering, King’s College London & Guy’s and St Thomas’ Hospital, London, United Kingdom
- ↵∗Reprint requests and correspondence:
Dr. Jonathan M. Behar, Imaging Sciences & Biomedical Engineering, St. Thomas’ Hospital, 4th Floor Lambeth Wing, London SE1 7EH, United Kingdom.
Objectives The purpose of this study was to identify the optimal pacing site for the left ventricular (LV) lead in ischemic patients with poor response to cardiac resynchronization therapy (CRT).
Background LV endocardial pacing may offer benefit over conventional CRT in ischemic patients.
Methods We performed cardiac magnetic resonance, invasive electroanatomic mapping (EAM), and measured the acute hemodynamic response (AHR) in patients with existing CRT systems.
Results In all, 135 epicardial and endocardial pacing sites were tested in 8 patients. Endocardial pacing was superior to epicardial pacing with respect to mean AHR (% change in dP/dtmax vs. baseline) (11.81 [-7.2 to 44.6] vs. 6.55 [-11.0 to 19.7]; p = 0.025). This was associated with a similar first ventricular depolarization (Q-LV) (75 ms [13 to 161 ms] vs. 75 ms [25 to 129 ms]; p = 0.354), shorter stimulation–QRS duration (15 ms [7 to 43 ms] vs. 19 ms [5 to 66 ms]; p = 0.010) and shorter paced QRS duration (149 ms [95 to 218 ms] vs. 171 ms [120 to 235 ms]; p < 0.001). The mean best achievable AHR was higher with endocardial pacing (25.64 ± 14.74% vs. 12.64 ± 6.76%; p = 0.044). Furthermore, AHR was significantly greater pacing the same site endocardially versus epicardially (15.2 ± 10.7% vs. 7.6 ± 6.3%; p = 0.014) with a shorter paced QRS duration (137 ± 22 ms vs. 166 ± 30 ms; p < 0.001) despite a similar Q-LV (70 ± 38 ms vs. 79 ± 34 ms; p = 0.512). Lack of capture due to areas of scar (corroborated by EAM and cardiac magnetic resonance) was associated with a poor AHR.
Conclusions In ischemic patients with poor CRT response, biventricular endocardial pacing is superior to epicardial pacing. This may reflect accessibility to sites that cannot be reached via coronary sinus anatomy and/or by access to more rapidly conducting tissue. Furthermore, guidance to the optimal LV pacing site may be aided by modalities such as cardiac magnetic resonance to target delayed activating sites while avoiding scar.
Wellcome Trust grant WT088641/Z/09/Z was awarded to Dr. Niedererin. Drs. Behar and Claridge acknowledge the fellowship support of the NIHR BRC at Guy’s and St Thomas’ NHS Foundation Trust.
Dr. Claridge has received research fellowship funding from St. Jude Medical Ltd. Dr. Jackson has received research fellowship funding from Medtronic Inc. Dr. Sohal has received an educational grant from St. Jude Medical Ltd. Dr. Rinaldi is consultant to St Jude Medical Ltd., Medtronic, and Spectranetics; and receives research funding from St Jude Medical and Medtronic.
- Received December 21, 2015.
- Revision received March 31, 2016.
- Accepted April 7, 2016.
- The Authors