PubMed · 5998677
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G Scharfenberg, E Winkelvoss, S Benndorf. 1966-10-01. [The inconstant bundle branch block].. https://pubmed.ncbi.nlm.nih.gov/5998677/
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BACKGROUND: Resting regional wall-motion abnormalities do not reliably distinguish ischemic from nonischemic cardiomyopathy. Dobutamine stress echocardiography with use of the wall-motion score index (WMSI) identifies coronary artery disease (CAD) in dilated cardiomyopathy (DCM), but the technique is subjective and further complicated by left bundle-branch block (LBBB). Long-axis motion is sensitive to ischemia and can be assessed quantitatively. We aimed to compare long-axis function with WMSI for detecting CAD in DCM with or without LBBB. METHODS AND RESULTS: Seventy-three patients with DCM, 48 with CAD (16 with LBBB), and 25 without CAD (10 with LBBB) were studied. Long-axis M-mode, pulsed-wave tissue Doppler echograms (lateral, septal, and posterior walls), and WMSI were assessed at rest and at peak dobutamine stress. Failure to increase systolic amplitude (total amplitude minus postejection shortening) by 2 mm or early diastolic velocity by 1.1 cm/s was the best discriminator for CAD (systolic amplitude, sensitivity 85%, specificity 86%; lengthening velocity, 71% and 94%, respectively; P=NS). Both had greater predictive accuracy than did WMSI (sensitivity 67%, specificity 76%; P<0.001). The predictive accuracy of changes in septal long-axis function was similar to those of average long-axis function (systolic amplitude cutoff=1.5 mm, lengthening velocity cutoff=1.5 cm/s). However in LBBB, systolic amplitude proved to be the only significant discriminator for CAD, with sensitivity and specificity reaching 94% and 100%, respectively (P<0.01 versus early diastolic lengthening velocity). CONCLUSIONS: Quantified stress long-axis function identifies CAD in DCM with greater sensitivity and specificity than does standard WMSI, particularly in the presence of LBBB.
Using Fourier phase analysis of equilibrium radionuclide angiography in both ventricles, inter- and intraventricular delays were correlated with QRS morphology and duration in 103 patients with idiopathic dilated cardiomyopathy. We found that left bundle branch block on the left axis may reflect a high intra-left ventricular dyssynchrony. A precise evaluation of the dyssynchrony appears useful because a high proportion of patients with incomplete bundle branch block, left anterior hemiblock, or "normal" QRS exhibit a marked intra-LV dyssynchrony and may respond to cardiac resynchronization therapy.
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