Abstract
AbstractBackgroundCardiac imaging-based indices of left ventricular (LV) mechanical dyssynchrony have limited accuracy for predicting the response to cardiac resynchronization therapy (CRT). The aim of the study was to evaluate the diagnostic performance of mechanical dyssynchrony indices in a study population of patients with severely reduced ejection fraction and no LV myocardial scar assessed by cardiovascular magnetic resonance (CMR), and either left bundle branch block (LBBB) or normal QRS duration.MethodsWe retrospectively identified 80 patients from three centers, with LV ejection fraction ≤35%, no scar by CMR late gadolinium enhancement, and either normal electrocardiographic QRS duration (<120ms) and normal frontal plane electrical axis (-30 to +90 degrees) (control, n=36), or LBBB by Strauss’ criteria (LBBB, n=44). The CMR image data from these subjects is made publicly available as part of this publication. CMR feature tracking was used to derive circumferential strain in a midventricular short-axis cine image. Using circumferential strain, mechanical dyssynchrony was quantified as the circumferential uniformity ratio estimate (CURE) and the systolic stretch index (SSI), respectively.ResultsBoth CURE and SSI resulted in measures of mechanical dyssynchrony that were more severe (lower CURE, higher SSI) in LBBB compared to controls (CURE, median [interquartile range], 0.63 [0.54-0.75] vs 0.79 [0.69-0.86], p<0.001; SSI 9.4 [7.4-12.7] vs 2.2 [1.2-3.6], p<0.001). SSI outperformed CURE in the ability to discriminate between LBBB and controls (area under the receiver operating characteristics curve [95% confidence interval] 0.98 [0.95-1.00] vs 0.77 [0.66-0.86], p<0.001; sensitivity 93 [84-100] vs 75 [61-86] %, p=0.02; specificity 97 [92-100] vs 67 [50-81] %, p=0.003).ConclusionsThe ability to discriminate between LBBB and normal QRS duration among patients with severely reduced ejection fraction and no scar was fair for CURE and excellent for SSI.
Publisher
Cold Spring Harbor Laboratory