title: Diastolic electromechanical coupling: association of the ECG T-peak to T-end interval with echocardiographic markers of diastolic dysfunction.
abstract: BACKGROUND
  Electromechanical coupling, a well-described phenomenon in systolic dysfunction, has not been well studied in diastole. We hypothesized that the ECG T-peak to T-end (TpTe) interval, representing transmural dispersion of repolarization, is associated with echocardiographic markers of diastolic dysfunction (DD).
  
  
  RESULTS
  We performed a prospective, cross-sectional study of the association between TpTe and markers of DD in 84 consecutive, unselected patients referred for exercise echocardiography. We systematically measured TpTe on the resting ECG, and we performed comprehensive assessment of DD at rest and at peak stress. ECGs and echocardiograms were analyzed independently, blinded to each other and to all clinical data. By univariable analysis, increased TpTe was associated with older age, increased E/e' ratio, and DD (P<0.05 for all associations after correcting for multiple comparisons). Increased TpTe was inversely associated with reduced tissue Doppler e' velocity, a marker of DD (R=-0.66, P<0.0001). This association persisted after adjusting for age, QTc, exercise-induced wall motion abnormalities, and left ventricular mass index (β=-0.41 [95% confidence interval, -0.70 to -0.12] cm/s per 10-ms increase in TpTe; P=0.006). Baseline TpTe was also independently associated with resting DD (adjusted odds ratio, 3.9 [95% confidence interval, 1.4-10.7]; P=0.009) and peak exercise E/e' ratio (P<0.0001).
  
  
  CONCLUSIONS
  Increased TpTe is associated with both resting and exercise-induced DD. Electromechanical coupling may represent a pathophysiologic link between electrical transmural dispersion of repolarization and abnormal myocardial relaxation, and may be a novel therapeutic target.
authors.affiliation: Division of Cardiology, Department of Medicine, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Sauer
authors.forename: Jane E
authors.initials: JE
authors.lastname: Wilcox
authors.forename: Adin-Cristian
authors.initials: AC
authors.lastname: Andrei
authors.forename: Rod
authors.initials: R
authors.lastname: Passman
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Goldberger
authors.forename: Sanjiv J
authors.initials: SJ
authors.lastname: Shah
mesh_terms: D003430:Cross-Sectional Studies; D003971:Diastole; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007087:Illinois / Q000453:epidemiology; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D011446:Prospective Studies; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology*