QT dispersion is determined by the relative extent of normal, hibernating, and scarred myocardium in patients with chronic ischemic cardiomyopathy. A dobutamine stress echocardiography study before and after surgical revascularization

J Electrocardiol. 2006 Jan;39(1):103-9. doi: 10.1016/j.jelectrocard.2005.07.007. Epub 2005 Nov 28.

Abstract

Introduction: The aim of the present study was to evaluate a possible association between QT dispersion (QTd) and the amount of viable and scarred myocardial tissue after revascularization in patients with coronary artery disease and impaired left ventricular (LV) function.

Methods: Twenty-two patients with ischemic LV dysfunction underwent dobutamine stress echocardiography (DSE) before and 6 months after surgical revascularization. Mean corrected QT-interval value and QTd were calculated at baseline and follow-up. Segments consisting of transmural scar were determined as the segments that remained akinetic in all stages of DSE despite reperfusion. Patients were divided into 2 groups according to the number of definitive segments consisting of transmural scar (minor scar group, < or =2 scarred segments; major scar group, >2 scarred segments).

Results: QTd was significantly lower in the minor compared with the major scar group at baseline and follow-up (mean [SD], 61 [22] vs 98 [33] milliseconds, P = .008, and 45 [18] vs 68 [21] milliseconds, P = .01, respectively). Segments consisting of transmural scar positively correlated to QTd at baseline (r = 0.53, P = .01) and follow-up (r = 0.62, P = .002).

Conclusions: QTd is positively correlated with the extent of scarred myocardial tissue assessed by DSE. Surgical revascularization results in reduction of QTd in all patients with hibernating myocardium and LV dysfunction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cardiomyopathies / physiopathology*
  • Cardiotonic Agents
  • Coronary Artery Bypass
  • Dobutamine
  • Echocardiography, Stress
  • Heart / physiopathology*
  • Heart Rate / physiology*
  • Humans
  • Myocardial Stunning / physiopathology*
  • Myocardium / pathology
  • Prospective Studies
  • Ventricular Dysfunction, Left / physiopathology*

Substances

  • Cardiotonic Agents
  • Dobutamine