Abstract 16642: Effects of Transmural Dispersion of Repolarization (Electrocardiographic T-peak to T-end Duration) on Myocardial Mechanics
Introduction: We recently reported that the T-peak to T-end interval (TpTe) is inversely related to tissue Doppler septal E' velocity (a marker of myocardial relaxation). We postulated that electromechanical coupling of transmural dispersion of repolarization (TDR) may partially account for abnormal mechanical function by mechanism of heterogeneous timing of the onset of myocardial relaxation. Acoustic markers of regional spatial displacement (strain imaging) differentiating endocardial, midmyocardial, and epicardial function can be used to demonstrate this phenomenon. We hypothesized that a longer TpTe would correlate with both increased time to peak strain (tPk-S) and increased heterogeneity of tPk-S (as measured by standard deviation [SD] in tPk-S).
Methods: We performed a prospective, cross-sectional study of the association between TpTe and tPk-S at the endocardial, midmyocardial, and epicardial regions involving 82 consecutive, unselected patients referred for echo. We measured TpTe on the resting ECG. In addition to full echo with Doppler, we performed speckle-tracking analysis recording longitudinal, circumferential, and radial strain as well as tPk-S for endocardial, midmyocardial, and epicardial regions.
Results: Subjects were a mean age of 52±14 yrs (44% female) and demonstrated a mean TpTe of 76±17 ms. Mean left ventricular ejection fraction was 60±4%. Mean QRS and QTc interval were 90±14 ms and 423±27 ms respectively. TpTe correlated with increased radial midmyocardial tPk-S as well as increased regional heterogeneity in tPk-S as measured by SD (P < 0.05). This relationship was not significant at the endocardial or epicardial regions. This association persisted after linear regression adjustments for age, heart rate, and QTc.
Conclusions: Increased TpTe is associated with both increased tPk-S and heterogeneous distribution of tPk-S. TDR among unselected patients may have mechanical implications and may be a target for therapy.
- © 2012 by American Heart Association, Inc.