The value of a new speckle tracking index including left ventricular global longitudinal strain and torsion in patients with dilated cardiomyopathy.

INTRODUCTION Torsional and longitudinal deformations are essential components of left ventricular (LV) performance. We believe that a precise assessment of LV function must take into account both LV torsion (LVtor) and global longitudinal strain (LVε). Therefore, we investigated with speckle tracking echocardiography the value of a new parameter, LVtor × LVε, for assessing LV function in dilated cardiomyopathy (DCM) and validated it against N-terminal pro-brain natriuretic peptide (NTproBNP). METHODS Echocardiography was performed simultaneously with NTproBNP determination in 55 consecutive patients with DCM in sinus rhythm. The ratio of early diastolic transmitral velocity to early mitral annular diastolic velocity (E/E') was measured. LVtor was defined as the ratio between LV twist (LVtw) and LV enddiastolic longitudinal length. LVtw (net difference between rotation angles at base and apex) was obtained from parasternal apical and basal short-axis planes. LVε was obtained by averaging longitudinal peak systolic strain of all 17 LV-segments (from apical planes). RESULTS Log-transformed NTproBNP correlated significantly with LVε (r=0.56, p<0.001), E/E' (r=0.52, p<0.001), LVtor (r=-0.41, p=0.003), LVtw (r=-0.38, p=0.004) and LV ejection fraction (r=-0.37, p=0.005). LVtor × LVε had the strongest correlation with log-NTproBNP (r=0.71, p<0.001). LVtor × LVε was a better predictor of NTproBNP levels >900 pg/ml (sensitivity 73%, specificity 82%) than LVε, E/E', LVtw, LVtor and LV ejection fraction (each p<0.05). CONCLUSIONS This study demonstrates that in patients with DCM in sinus rhythm, the evaluation of LV function can be accurately accomplished by using a new speckle tracking index, LVtor × LVε.