title: Impact of myocardial viability and left ventricular lead location on clinical outcome in cardiac resynchronization therapy recipients with ischemic cardiomyopathy.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) recipients with ischemic cardiomyopathy (ICM) have scar segments that may limit ventricular resynchronization and clinical response. The impact of myocardial viability at the left ventricular (LV) pacing site on CRT response is poorly elucidated.
  
  
  RESULTS
  A retrospective cohort of 160 ICM patients with single photon emission computed tomography-myocardial perfusion imaging before device implantation were included. Coronary venous angiography and chest radiographs helped classify segmental location of LV lead (LVL). The primary outcome was a composite of heart failure (HF) hospitalization and mortality at 3 years, and secondary outcome was change in systolic function at 6 months. The patients were divided into groups based on the myocardial substrate at the site of LVL: LVL on or adjacent to (1) normal myocardium (LVL-N, n = 64), (2) segmental scar (LVL-S, n = 62), and (3) scar and ischemia (LVL-SI, n = 34). Upon follow-up, 75 (47%) patients reached primary endpoint with a higher incidence noted in LVL-S (60%), and LVL-SI (53%), compared to 31% in LVL-N (P = 0.004). Kaplan Meier method demonstrated poor event free survival for primary outcome in LVL-S (P = 0.002), and LVL-SI (P = 0.03). In Cox proportional hazard model, LVL-S (HR: 2.26, P = 0.004), and LVL-SI (1.9, P = 0.047) were independent predictors of primary outcome.
  
  
  CONCLUSIONS
  In CRT recipients with ICM, scar and reversible ischemia in or adjacent to LV pacing site were independent predictors of HF hospitalization and death.
authors.affiliation: Cardiac Arrhythmia Service.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Bose
authors.affiliation: Cardiac Arrhythmia Service.
authors.forename: Jagdesh
authors.initials: J
authors.lastname: Kandala
authors.affiliation: Cardiac Arrhythmia Service.
authors.forename: Gaurav A
authors.initials: GA
authors.lastname: Upadhyay
authors.affiliation: Cardiac Arrhythmia Service.
authors.forename: Lindsay
authors.initials: L
authors.lastname: Riedl
authors.affiliation: Nuclear Cardiology Service, Division of Cardiology, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Imad
authors.initials: I
authors.lastname: Ahmado
authors.affiliation: Nuclear Cardiology Service, Division of Cardiology, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Ram
authors.initials: R
authors.lastname: Padmanabhan
authors.affiliation: Nuclear Cardiology Service, Division of Cardiology, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Henry
authors.initials: H
authors.lastname: Gewirtz
authors.affiliation: Therapy Delivery Research, Medtronic, Minneapolis, Minnesota, USA.
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Mulligan
authors.affiliation: Cardiac Arrhythmia Service.
authors.forename: Jagmeet P
authors.initials: JP
authors.lastname: Singh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects / Q000401:mortality; D058409:Cardiac Resynchronization Therapy Devices; D009202:Cardiomyopathies / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D016009:Chi-Square Distribution; D002921:Cicatrix / Q000175:diagnosis / Q000209:etiology*; D017023:Coronary Angiography; D018572:Disease-Free Survival; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000209:etiology / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D006760:Hospitalization; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications* / Q000175:diagnosis / Q000401:mortality; D055414:Myocardial Perfusion Imaging / Q000379:methods; D009206:Myocardium / Q000473:pathology*; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D014022:Tissue Survival; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling
keywords: cardiac resynchronization therapy; heart failure; implantable cardioverter defibrillator; ischemia; myocardial scar