title: QRS morphology and ventricular dyssynchrony in patients with chronic right ventricular pacing.
abstract: BACKGROUND
  Mechanical dyssynchrony (MD) is associated with poor outcomes in many different populations. However, the predictors for the development of MD after chronic right ventricular (RV) pacing are not well known.
  
  
  METHODS
  Pacing QRS morphology and MD using echocardiography was analyzed in 175 consecutive patients that have pacemaker implantation during a 7.6 year median follow-up. Predictive score for MD was constructed using QRS morphology variables and calculated by summing the points of the 4 variables: duration (≥150 ms, 1 point), transition (1 point), notching (2 points), and left-axis deviation (1 point), based on a multivariate-adjusted risk relationship with MD.
  
  
  RESULTS
  Sixty-eight (38.9%) patients developed MD. Patients with MD had worsened left ventricular systolic function (ejection fraction from 64.6±10.6% to 59.1±10.4%, p<0.001) and heart failure symptoms (New York Heart Association functional class increase from 1.1±0.3 to 1.9±0.8, p<0.001). In an electrocardiographic analysis, QRS duration≥150 ms, the presence of precordial axis transition, notching, and left-axis deviation were strongly associated with MD. Predictive score for MD using QRS morphology parameters displayed an excellent graded relationship with MD (score 0: 3.4% vs. 1: 12.5% vs. 2: 22.6% vs. 3: 45.0% vs. 4: 57.9% vs. 5: 72.7%, linear p<0.001) (model performance c-static 0.78, 95% confidence interval 0.72-0.85, p<0.001).
  
  
  CONCLUSIONS
  Patients with MD experienced a decline in left ventricular systolic function and an increase in heart failure symptoms after chronic RV pacing. A new scoring system using QRS morphology is considered a simple and efficient tool for predicting the development of MD after chronic RV pacing.
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Ki Hong
authors.initials: KH
authors.lastname: Lee
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea. Electronic address: chojg@unitel.co.kr.
authors.forename: Jeong Gwan
authors.initials: JG
authors.lastname: Cho
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Hyung Wook
authors.initials: HW
authors.lastname: Park
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Nam Sik
authors.initials: NS
authors.lastname: Yoon
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Kim
authors.affiliation: Chunnam Technology University, Gokseong, South Korea.
authors.forename: Mi Ran
authors.initials: MR
authors.lastname: Kim
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Min Chul
authors.initials: MC
authors.lastname: Kim
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Kyung Hoon
authors.initials: KH
authors.lastname: Cho
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Hyun Kuk
authors.initials: HK
authors.lastname: Kim
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Cheol Hwan
authors.initials: CH
authors.lastname: Kim
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Kyung Hwan
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Seung Jin
authors.initials: SJ
authors.lastname: Jun
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Kim
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Kyoung Jin
authors.initials: KJ
authors.lastname: Lee
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Hae Chang
authors.initials: HC
authors.lastname: Jeong
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Jae Yeong
authors.initials: JY
authors.lastname: Cho
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Keun-Ho
authors.initials: KH
authors.lastname: Park
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Doo sun
authors.initials: Ds
authors.lastname: Sim
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Hyun Ju
authors.initials: HJ
authors.lastname: Yoon
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Kye Hun
authors.initials: KH
authors.lastname: Kim
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Young Joon
authors.initials: YJ
authors.lastname: Hong
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Ju Han
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Youngkeun
authors.initials: Y
authors.lastname: Ahn
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Myung Ho
authors.initials: MH
authors.lastname: Jeong
authors.affiliation: Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Jong Chun
authors.initials: JC
authors.lastname: Park
mesh_terms: D000368:Aged; D054537:Atrioventricular Block / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects* / Q000379:methods; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012804:Sick Sinus Syndrome / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology
keywords: Cardiac pacing; Electrocardiography; Heart failure; Mechanical dyssynchrony; Pacemaker