title: Optimized Left Ventricular Endocardial Stimulation Is Superior to Optimized Epicardial Stimulation in Ischemic Patients With Poor Response to Cardiac Resynchronization Therapy: A Combined Magnetic Resonance Imaging, Electroanatomic Contact Mapping, and Hemodynamic Study to Target Endocardial Lead Placement.
abstract: OBJECTIVE
  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/dtmaxvs. 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.
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Behar
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Tom
authors.initials: T
authors.lastname: Jackson
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Eoin
authors.initials: E
authors.lastname: Hyde
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Simon
authors.initials: S
authors.lastname: Claridge
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Jaswinder
authors.initials: J
authors.lastname: Gill
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Julian
authors.initials: J
authors.lastname: Bostock
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Manav
authors.initials: M
authors.lastname: Sohal
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Bradley
authors.initials: B
authors.lastname: Porter
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: O'Neill
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Reza
authors.initials: R
authors.lastname: Razavi
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Steve
authors.initials: S
authors.lastname: Niederer
authors.affiliation: Department of Imaging Sciences and Biomedical Engineering, King's College London & Guy's and St Thomas' Hospital, London, United Kingdom.
authors.forename: Christopher Aldo
authors.initials: CA
authors.lastname: Rinaldi
keywords: AHR, acute hemodynamic response; CMR, cardiac magnetic resonance; CRT; CRT, cardiac resynchronization therapy; EAM, electroanatomic mapping; LV, left ventricle/ventricular; LVendo, left ventricular endocardium; LVepi, optimal epicardial response; LVepi1, implanted LV lead; LVepi2, temporary LV lead; Q-LV, first ventricular depolarization; cardiac magnetic resonance imaging; electroanatomic map; endocardial pacing