Myocardial integrated ultrasonic backscatter in patients with dilated cardiomyopathy: Prediction of response to beta-blocker therapy

Background Myocardial integrated backscatter (IB) imaging has been reported to be useful for ultrasonic tissue characterization and delineation of myo cardial viability or fibrosis. beta-Blocker therapy has beneficial effects for patients with dilated cardiomyopathy (DCM), but there are no clear find ings that indicate which patients with DCM will respond to this therapy. Th is study was performed to evaluate whether myocardial IB analysis can predi ct the response to beta-blocker therapy. Methods and Results We prospectively performed echocardiographic examinatio n with IB analysis in 29 patients with DCM (20 men, 9 women) before startin g bisoprolol therapy and in 15 normal subjects. Standard echocardiographic examination and IB analysis in the left ventricular wall in the 2-dimension al short-axis view were performed and the magnitude of cyclic variation (CV ) of IB and calibrated myocardial IB intensity (subtracted pericardial) wer e obtained from the interventricular septum and the left ventricular poster ior wall. Sixteen patients responded to bisoprolol therapy and 13 did not r espond after 12 months of full-dose therapy. Calibrated myocardial IB inten sity was lower in responders relative to nonresponders in both the interven tricular septum (responders, -20.1 +/- 3.6 dB vs nonresponders, -9.8 +/- 5. 1 dB, P <.0001; controls, -20.1 +/- 4.4 dB) and posterior wall (responders, -20.6 +/- 3.6 dB vs nonresponders, -14.6 +/- 4.2 dB P =.0002; controls, -2 2.7 +/- 3.3 dB). Also, the lower the myocardial intensity in the interventr icular septum or posterior wall, the better left ventricular systolic funct ion improved after beta-blocker therapy. However, CV was lower in both DCM groups than in the controls, and CV in the interventricular septum was lowe r in nonresponders than in responders (responders, 4.0 +/- 4.1 dB vs nonres ponders, -0.8 +/- 6.1 dB, P <.02; controls, 8.3 +/- 2.4 dB). In addition, C V in the posterior wall showed no difference between the 2 DCM groups (resp onders, 5.6 +/- 1.3 dB vs nonresponders, 5.1 +/- 3.5 dB, P = not significan t; controls, 9.6 +/- 2.5 dB). Also, the percent fibrosis on right ventricul ar endomyocardial biopsy specimens showed no distinctions between these 2 g roups (responders, 25.1% +/- 16.1% vs nonresponders, 24.9% +/- 15.0%, P = n ot significant). Conclusions These findings suggest that left ventricular myocardial IB data , especially IB intensity, provide useful information for predicting the re sponse to beta-blocker therapy in patients with DCM. However, right ventric ular endomyocardial biopsy findings do not appear to contribute to discrimi nating between the 2 groups.