Cardiovascular magnetic resonance-derived metrics as diagnostic markers for left ventricular outflow tract obstruction in hypertrophic cardiomyopathy

Figures

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  Fig. 1. Measurements in the three-chamber balanced steady-state free precession cine images in hypertrophic cardiomyopathy patients. Top row: three-chamber balanced steady-state free precession (bSSFP) cine images of a hypertrophic cardiomyopathy (HCM) patient with no left ventricular outflow tract (LVOT) obstruction in mid-systole (a) and end-systole (b). Bottom row: three-chamber bSSFP cine images of an HCM patient with LVOT obstruction in mid-systole (c) and end-systole (d). Red arrow: presence of flow artifact in LVOT during systole; red circles: regions of interest (ROI) for signal intensity measurements. Mean signal intensity was measured manually in ROIs of approximately 0.5 cm2 at end-systole in the LVOT, left ventricle, and left atrium (1–2 cm above the mitral valve). In cases of mitral regurgitation, the ROI in left atrium was adjusted to avoid the mitral regurgitation jet; red line: the shortest distance between the mitral valve leaflet tip and the interventricular septum. Left ventricular volumes were measured on the short-axis cine images using standard methods, including the papillary muscles and trabeculations in the blood volume. LV stroke volume was calculated by…

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  Fig. 2. Study flowchart. CMR cardiovascular magnetic resonance, HCM hypertrophic cardiomyopathy

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  Fig. 3. Comparison of the minimum distance between the mitral leaflet tip and the interventricular septum between hypertrophic cardiomyopathy patients with and without left ventricular outflow tract obstruction, stratified by sex. (A) Distance in mm, (B) distance indexed by body surface area in mm/m2. LVOTO left ventricular outflow tract obstruction, Minimum MV-IVS distance minimum mitral valve leaflet tip to interventricular septum distance, Minimum MV-IVSi distance minimum mitral valve leaflet tip to interventricular septum distance indexed

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  Fig. 4. Receiver operating characteristic curve analyses of different cardiovascular magnetic resonance variables for discriminating left ventricular outflow tract obstruction on echocardiography. (A and C) Receiver operating characteristic curve analyses of the univariable and multivariable models developed and evaluated on the training cohort (A, n = 359) and validation cohort (C, n = 89); (B and D) Receiver operating characteristic curve analyses of univariable and multivariable models developed on the training cohort and evaluated on a subset of the training and validation cohort after excluding patients with LVOT obstruction at rest (B, training cohort, n = 263 and D, validation cohort, n = 64). AUC area under the curve, CI confidence interval, LV left ventricle, LVOT left ventricle outflow tract, Minimum MV-IVSi distance minimum mitral valve leaflet tip to interventricular septum distance indexed, ROC receiver operating characteristic, SVi stroke volume indexed

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  Fig. 5. Distribution of the minimum distance between the mitral leaflet tip and the interventricular septum in the total population across three subgroups: no left ventricular outflow tract obstruction (LVOTO), LVOTO at rest, and LVOTO during provocation. (A) Distance in mm, (B) distance indexed by body surface area in mm/m2. LVOTO left ventricular outflow tract obstruction, Minimum MV-IVS distance minimum mitral valve leaflet tip to interventricular septum distance, Minimum MV-IVSi distance minimum mitral valve leaflet tip to interventricular septum distance indexed