P358The effect of myocardial fibrosis on left ventricular torsion / twist in patients with non-ischemic dilated cardiomyopathy: a cardiovascular magnetic resonance imaging and echocardiography study

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Purpose: LV rotation, twist, and torsion are important aspects of the cardiac performance. Rotation of the LV apex relative to the base is related to the myocardial contractility, furthermore, the potential energy stored by LV twist during the systolic phase is rapidly released during LV untwisting and constitutes an important determinant of diastolic suction and diastolic function. Myocardial fibrosis can be also identified as late gadolinium enhancement (LGE) areas with cardiac magnetic resonance (CMR) studies. However, there is limited information about the association of myocardial fibrosis and left ventricular rotational parameters.Methods and Results: Twenty-two patients with nonischemic DC (NDC) and sinus rhythm and LV EF < 40% were enrolled. LV regional deformation, twist and untwist rate were measured using two-dimensional speckle tracking imaging (2D-STI) method. Myocardial fibrosis identified as late gadolinium enhancement (LGE) areas with CMR. Myocardial fibrosis severity defined by calculation of MR-index. The patients were sub-grouped into two groups based on the absence (LGE-) and presence (LGE+) of fibrosis. LV regional deformation were similar whereas LV rotational parameters were significantly different between two groups. LGE+ patients have significantly greater basal systolic rotation, significantly lower apical systolic rotation, Torsion and Torsion/LV length values than patients in LGE-. Untwist rate were similar. Torsion/LV length was moderately correlated with LVEF and MR-index. Linear regression analysis revealed that only MR-index (OR: 1.53, 95% CI: 2.9–3.06, P = 0.02) was independent correlated factors of Torion/LV length. Sixteen patients had normal directions of both basal (negative) and apical (positive) systolic rotations. Interestingly and significantly contrary to LGE- subjects, 5 patients with LGE+ had opposite (negative) apical systolic rotation. Compared with patients with the normal direction of apical systolic rotation, those with negative apical systolic rotation had significantly greater NT-proBNP values (1547±945 pg/ml vs 389±303 pg/ml, p=0.007), basal systolic rotation (-6.78±1.21 degree vs -3.06±2.2 degree, p < 0.001), lower apical systolic rotation (-3.71±3.64 degree vs 4.36±2.81 degree, p<0.001), Torsion (3.07±3.44 degree vs 7.43±2.72 degree, p=0.04), Torsion/LV length (0.35±0.51 degree/cm vs 0.95±0.38 degree/cm, p=0.05), MR-index (0.66±0.20 vs 0.95±0.06, p=0.03).Conclusion: Detection of myocardial fibrosis can be a useful indicator for the evaluation of LV mechanics and NDC patients with LV fibrosis have impaired LV systolic Rotation and Torsion parameters.

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