Background and Objectives：Electrical dyssynchronicity (Dsyn) appears to be prognostic of survival in congestive heart failure (CHF). Recent study has shown some discrepancy between the electrical Dsyn and the Doppler tissue image (DTI) assessed mechanical Dsyn. The aim of our study was to evaluate the relationship between the QRS duration and DTI assessed Dsyn.
Subjects and Methods：One hundred and forty patients, with CHF and left ventricular ejection fractions ≤40%, were enrolled. DTI was performed on 5-basal and 5-mid segments to assess the time from the R-wave to the peak systolic velocity (RS time). A QRS duration >130 msec, standard deviation (SD) of the RS time >40 msec, or a difference in the maximal and minimal RS times (RS time-diff) >100 msec were indicators of ‘Dsyn’.
Results：The prevalence of myocardial Dsyn, by QRS duration, SD of the RS time and the RS time-diff were 19, 43 and 47%, respectively. The SD of the RS time (49.8±23.6 vs. 36.6±20.7, p<0.01) and the RS time-diff (139.2±63.2 vs. 98.0±54.3, p<0.01) were prolonged in the wide (>130 msec) compared with the narrow QRS group. There was also a weak positive correlation between the QRS duration and the SD of the RS time (R=0.34, p<0.001) and the RS time-diff (R=0.38, p<0.001). However, from a cross-tabulation analysis, more than one third of patients had a discrepancy between QRS duration and DTI assessed mechanical Dsyn. From a multivariate analysis, a major determinant of the SD of the RS time was the QRS duration.
Conclusion：Although a major determinant of the DTI assessed Dsyn was the QRS duration, more than one-third of patients had a discrepancy between electrical and mechanical Dsyn. Therefore, not only the QRS duration, but the DTI assessed Dsyn, should be measured when considering cardiac resynchronization therapy.
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