title: Role of shortened QTc dispersion in in-hospital cardiac events in patients undergoing percutaneous coronary intervention for acute coronary syndrome.
abstract: BACKGROUND
  QT dispersion (QTD) refers to the difference between maximal and minimal QT values on the electrocardiogram (ECG). QTD values are calculated and corrected with Bazett's formula (corrected QTD = QTcD = QTD/square root of RR). QTcD increases in patients with acute coronary syndrome (ACS). Recovery of increased QTcD (shortened QTcD) develops after successful revascularization, but prolonged QTcD occurs in certain patients. The aim of this study is to ascertain the clinical significance between shortened and prolonged QTcD groups after percutaneous coronary intervention (PCI).
  
  
  METHODS
  We retrospectively enrolled 128 patients with ACS who had received PCI. The values of QTcD were measured manually on 12-lead standard ECGs obtained within 3 days before and after PCI (pre-PCI QTcD and post-PCI QTcD). All the patients were divided into 2 groups. The shortened QTcD group was defined as those patients with a decrease in QTcD after PCI and the prolonged QTcD group as those with an increase in QTcD after PCI. The underlying diseases, various clinical classifications and some prognostic factors were taken into comparison and statistical analysis between these 2 groups.
  
  
  RESULTS
  The shortened QTcD group showed a significantly higher rate of in-hospital cardiac death (13% vs. 0%, p = 0.006) and a greater pre-PCI QTcD (100.8 +/- 39.5 vs. 61.3 +/- 24.1 ms, p < 0.001) than the prolonged QTcD group. There was a significantly greater pre-PCI QTcD in patients with cardiac death than those without cardiac death (111.6 +/- 38.3 vs. 83.3 +/- 38.3ms, p = 0.027). Furthermore, the patients with in-hospital cardiac death presented with a significantly more frequent occurrence of in-hospital ventricular arrhythmia, compared with those without cardiac death (30.0% vs. 4.0%, p = 0.014).
  
  
  CONCLUSIONS
  Among the patients with ACS undergoing PCI, directly divided into shortened and prolonged QTcD groups regardless of initial pre-PCI QTcD, the shortened QTcD group showed a higher occurrence of in-hospital cardiac death and a greater pre-PCI QTcD. Shortened QTcD might be 1 risk factor for in-hospital cardiac death.
authors.affiliation: Division of Cardiology, Department of Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, ROC.
authors.forename: Chi-Cheng
authors.initials: CC
authors.lastname: Lai
authors.forename: Hsiang-Chiang
authors.initials: HC
authors.lastname: Hsiao
authors.forename: Shin-Hung
authors.initials: SH
authors.lastname: Hsiao
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Huang
authors.forename: Chuen-Wang
authors.initials: CW
authors.lastname: Chiou
authors.forename: Tung-Cheng
authors.initials: TC
authors.lastname: Yeh
authors.forename: Hwong-Ru
authors.initials: HR
authors.lastname: Hwang
authors.forename: Doyal
authors.initials: D
authors.lastname: Lee
authors.forename: Guang-Yuan
authors.initials: GY
authors.lastname: Mar
authors.forename: Shih-Kai
authors.initials: SK
authors.lastname: Lin
authors.forename: Kuan-Rau
authors.initials: KR
authors.lastname: Chiou
authors.forename: Shoa-Lin
authors.initials: SL
authors.lastname: Lin
authors.forename: Chun-Peng
authors.initials: CP
authors.lastname: Liu
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D003327:Coronary Disease / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D004562:Electrocardiography; D005260:Female; D006323:Heart Arrest / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D017180:Tachycardia, Ventricular / Q000209:etiology; D014693:Ventricular Fibrillation / Q000209:etiology