title: Association of QRS duration and survival in dogs with dilated cardiomyopathy: a retrospective study of 266 clinical cases.
abstract: OBJECTIVE
  The purpose of this study was to investigate the prognostic value of QRS duration in dogs with dilated cardiomyopathy (DCM) by studying its relationship with survival time.
  
  
  METHODS
  The medical records of dogs diagnosed with DCM were retrospectively searched for good quality ECG tracings. The QRS duration was measured from the ECG tracing and two different models were used: binary variable (dogs were divided into 2 groups based on a QRS duration of <60 ms or ≥60 ms) and continuous variable. The survival times were analysed by the Kaplan-Meier method and Cox's proportional hazard model.
  
  
  RESULTS
  266 dogs met the inclusion and exclusion criteria. A QRS duration ≥60 ms was associated with a reduced survival time compared to those with a QRS duration <60 ms (Hazard Ratio of 1.34, 95% CI 1.05-1.71, P = 0.02). When considered as a continuous variable the Hazard Ratio was 1.015 for each increase in QRS duration of 1 ms (95% CI 1.006-1.024, p = 0.001).Dogs with a QRS duration < 60 ms had a median survival time (IQ range) of 25 weeks (97-65) and dogs with a QRS duration ≥60 ms had a median survival time (IQ range) of 13 weeks (3-34).
  
  
  CONCLUSIONS
  The measurement of QRS duration is relatively simple to perform from a surface ECG recording. A duration ≥60 ms is associated with shorter survival times in dogs with DCM, which may provide practitioners with additional prognostic information.
authors: Av. Fortunato Meneres 31, Santa Maria da Feira, Portugal. brigitepedro@hotmail.com
authors: Brigite M
authors: BM
authors: Pedro
authors: Joana V
authors: JV
authors: Alves
authors: Peter J
authors: PJ
authors: Cripps
authors: Mike J
authors: MJ
authors: Stafford Johnson
authors: Mike W S
authors: MW
authors: Martin
mesh_terms: D000818:Animals; D002311:Cardiomyopathy, Dilated / Q000401:mortality / Q000503:physiopathology / Q000662:veterinary*; D004283:Dog Diseases / Q000401:mortality / Q000503:physiopathology*; D004285:Dogs; D004562:Electrocardiography / Q000662:veterinary; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis