Background: Using speckle tracking echocardiography we investigated left ventricular (LV) twist and rotation (ROT) at the papillary muscle (PM) level and their correlation with standard echocardiographic and demographic parameters.
Aim: To assess whether the fulcrum of LV short axis ROT is shifted in myocardial disease.
Methods: The study group consisted of 33 patients (54+/-13 years old, 18 women). Left ventricular systolic function was normal in 6, and various degrees of wall motion abnormalities were present in the others [LV ejection fraction (LVEF) 49+/-15, wall motion score index (WMSI) 1.43+/-0.38]. Short axis images at basal, PM and apical level were analysed offline. The direction of ROT was determined from the apical aspect and expressed in degrees: clockwise (CW) in negative values, counter CW in positive. Twist is the arithmetic difference between apical and basal ROT.
Results: Left ventricular twist was in the range of 0.4-27.5 (14+/-7) degrees and correlated with LV systolic diameter (LVS), r=-0.46, 95% CI from -0.69 to -0.13, p <0.01; LV diastolic diameter (LVD), r=-0.40, 95% CI from -0.65 to -0.06, p=0.02; and systolic motion score index of 6 mid segments (6S-MSI), calculated as WMSI at PM level, r=-0.37, 95% CI from -0.63 to -0.03, p <0.04. Linear regression resulted in a model including interventricular septum systolic thickness (IVSS) and 6S-MSI, which predicted twist correctly in 21% of cases. Twist was independent of LVEF and overall WMSI. The PM ROT value correlated with: apical ROT, r=0.36, 95% CI 0.02-0.63, p <0,04; posterior wall systolic thickness (PWS), r=0.39, 95% CI 0.05-0.64, p <0.03. We distinguished Group A, n=14, with CW direction of PM ROT - negative values, range from -5.2 to -0.9; Group B, n=19, with counter CW, range 0.4-4.9. Apical ROT was 5 vs. 10 degrees, p <0.03; PWS 14 vs. 15 mm, p <0.03; diastolic posterior wall thickness 10 vs. 12 mm, p <0.04, respectively. In univariate logistic regression, we identified independent factors related to counter CW PM ROT: apical ROT (OR=1.15, 95% CI 1.00-1.33, p <0.05) and PWS (OR=1.71, 95% CI 1.03-2.84, p <0.04). Multiple logistic regression resulted in a model predicting counterCW rotation at PM (p <0.01) including: apical ROT (OR=1.18, 95% CI 1.00-1.38, p <0.05) and PWS (OR=1.77, 95% CI 1.02-3.08, p <0.05). ROC curves identified cut-off values of apical ROT >11.3 deg and PWS >13 mm. We found counterCW PM ROT in all patients with both conditions, 59% of patients with one, 22% with none.
Conclusions: Left ventricular twist is related to mid segments function and IVSS, while PM ROT value and its direction (associated with 'zero ROT level') is related to PWS and apical ROT, rather than to LVEF or WMSI. Thus twist and rotation may reflect novel aspects of LV function.