Interventricular mechanical dyssynchrony: quantification with velocity-encoded MR imaging

PURPOSE: To evaluate the performance of velocity-encoded (VENC) magnetic resonance (MR) imaging, as compared with pulsed-wave echocardiography (PW-ECHO), in the quantification of interventricular mechanical dyssynchrony (IVMD) as a predictor of response to cardiac resynchronization therapy (CRT).

MATERIALS AND METHODS: The study was approved by the local ethics committee, and all patients provided written informed consent. The study involved the examination of 45 patients (nine women, 36 men; median age, 60 years; interquartile age range, 47-69 years) with New York Heart Association class 2.0-3.0 heart failure and a reduced left ventricular ejection fraction (median, 25%; interquartile range, 21%-32%), with (n = 25) or without (n = 20) left bundle branch block. Aortic and pulmonary flow curves were constructed by using VENC MR imaging and PW-ECHO. IVMD was defined as the difference between the onset of aortic flow and the onset of pulmonary flow. Intraclass correlation coefficient, Spearman correlation coefficient, Bland-Altman, and Cohen kappa analyses were used to assess agreement between observers and methods.

RESULTS: Inter- and intraobserver agreement regarding VENC MR imaging IVMD measurements was very good (intraclass r = 0.96, P < .001; mean bias, -3 msec +/- 11 [standard deviation] and 0 msec +/- 10, respectively). A strong correlation (Spearman r = 0.92, P < .001) and strong agreement (mean difference, -6 msec +/- 16) were found between VENC MR imaging and PW-ECHO in the quantification of IVMD. Agreement between VENC MR imaging and PW-ECHO in the identification of potential responders to CRT was excellent (Cohen kappa = 0.94).

CONCLUSION: VENC MR measurements of IVMD are equivalent to PW-ECHO measurements and can be used to identify potential responders to CRT.