Additive value of torsion to global longitudinal left ventricular strain in patients with reduced ejection fraction.

BACKGROUND: Torsional and longitudinal deformations are essential components of left ventricular (LV) performance. A precise assessment of LV function must take into account both LV torsion (LVtor) and global longitudinal strain (LVE). We compared a new 2D-strain parameter, LVtor x LVE, with several other echocardiographic parameters, with respect to their strength of association with N-terminal pro-brain natriuretic peptide (NTproBNP) in patients with reduced LV ejection fraction (LVEF).

METHODS: Echocardiography was performed simultaneously with NTproBNP determination in 78 consecutive patients with reduced LVEF (<50%) in sinus rhythm. Early diastolic transmitral velocity/early mitral annular diastolic velocity ratio (E/E') and systolic mitral annular velocity (S') were measured. LVtor was defined as the ratio between LV twist (LVtw) and LV end-diastolic longitudinal length. LVtw (net difference between rotation angles at base and apex) was obtained from parasternal apical and basal short-axis planes. LVE was obtained by averaging longitudinal peak systolic strain of all 17 LV-segments (from apical planes).

RESULTS: Log-transformed NTproBNP correlated significantly with LVE (r = 0.57, P < 0.001), myocardial performance index (r = 0.56, P < 0.001), systolic pulmonary artery pressure (r = 0.47, P < 0.001), E/E' (r = 0.41, P < 0.001), LVtor (r = -0.37, P = 0.001), E-velocity deceleration time (r = -0.37, P = 0.003), S' (r = -0.36, P = 0.002), LVtw (r = -0.34, P = 0.003), LVEF (r = -0.34, P = 0.003), E/A (A = late diastolic transmitral velocity, r = 0.30, P = 0.01) and E (r = 0.28, P = 0.03). LVtor x LVepsilon had the strongest correlation with log-NTproBNP (r = 0.70, P < 0.001). LVtor x LVepsilon was a better predictor of NTproBNP > 900 pg/ml (sensitivity = 82%, specificity = 84%) than other investigated parameters (each P < 0.05).

CONCLUSIONS: In patients with reduced LVEF, LVtor x LVE is a promising parameter that deserves research to establish its clinical meaning and prognostic value.