title: Echocardiographic and clinical response to cardiac resynchronization therapy in heart failure patients with and without previous right ventricular pacing.
abstract: OBJECTIVE
  Right ventricular pacing (RVp) results in an electrocardiographic left bundle branch block pattern and can lead to heart failure. This study aimed to evaluate echocardiographic and clinical outcomes of heart failure patients with RVp upgraded to cardiac resynchronization therapy (CRT), as they are frequently excluded from multicentre studies.
  
  
  RESULTS
  This observational study assessed 655 consecutive patients with QRS ≥120 ms and left ventricular ejection fraction ≤35%. There were 465 patients without significant previous RVp and 190 with RVp >40%. Echocardiograms were analysed pre-CRT and ∼ 1 year post-CRT. Death and heart failure hospitalizations were analysed using Cox regression, adjusted for baseline characteristics. The RVp patients had smaller end-systolic volume (P = 0.002), were older (P < 0.001), and had more atrial fibrillation (P < 0.001) pre-CRT. Ejection fraction and proportion of ischaemic aetiology were similar. One year following CRT implantation the ejection fraction response was greater in the RVp group (8.3 ± 9 vs. 5.8 ± 9 units, P = 0.005). The RVp patients had an adjusted 33% lower risk of death or heart failure hospitalization [hazard ratio (HR) 0.67 95% confidence interval (CI) 0.51-0.89, P = 0.005], while tending to have an adjusted lower risk of death (HR 0.73 95% CI 0.53-1.01, P = 0.055).
  
  
  CONCLUSIONS
  Despite similar ejection fraction pre-CRT, patients upgraded to CRT with previous RVp have smaller end-systolic volume and respond to CRT at least as well as, if not better than, other wide QRS heart failure patients. A greater improvement in ejection fraction and a lower risk of death or heart failure hospitalization when adjusted for baseline characteristics were seen in those with previous RVp.
authors.affiliation: Research Division, United Heart & Vascular Clinic, 225 N. Smith Avenue, #400, St Paul, MN, USA.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Gage
authors.forename: Kevin V
authors.initials: KV
authors.lastname: Burns
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Bank
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D058406:Cardiac Resynchronization Therapy; D004452:Echocardiography; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy*; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D012307:Risk Factors; D013318:Stroke Volume; D015996:Survival Rate; D016896:Treatment Outcome; D018497:Ventricular Dysfunction, Right / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy*
keywords: cardiac resynchronization therapy; echocardiography; heart failure; outcomes; right ventricular pacing