Purpose: Previous study suggested that global strain rate measured during isovolumic relaxation (IVR) period related well to hemodynamic indices of left ventricular relaxation both in animal model and in patients. Therefore, the purpose of this study was to clarify the relationships between diastolic strain rates and global diastolic function in patients with hypertrophic cardiomyopathy (HCM), and compared 2-dimensional speckle tracking parameters with patients who have shown dobutamine induced left ventricular outflow tract (LVOT) obstruction and normal control subjects.
Methods: 14 patients with HCM (group 1: 64 ± 9 years), 14 patients with dobutamine induced LVOT obstruction (group 2: 60 ± 10 years), and 10 healthy control subjects (group 3: 49 ± 9 years) were investigated. Standard echocardiogram with tissue Doppler image was performed. Peak early diastolic strain rate (E SR), peak strain rate IVR period (IVR SR), peak late diastolic strain rate (A SR) were measured by 2-dimensional speckle tracking from left ventricular myocardium in study subjects using off-line analysis.
Results: Although study populations’ ejection fraction were normal (>55%, not significant), delayed IVR period, reduced longitudinal strain rates were noted in group 1 compared with group 2 and 3 (p<0.05, respectively). IVR SR showed significant positive correlation with E/A, and presented negative correlation with E/E’. E SR, E SR/A SR also showed significant positive correlation with E/A (r = 0.734, p < 0.001; r = 0.724, p < 0.001, respectively), and exhibited negative correlation with E/E’ (r = -0.695, p < 0.001; r = -0.624, p < 0.001, respectively). On the basis of receiver operating characteristics (ROC) curve analysis, optimal cutoff value of -0.01 % for IVR SR was chosen to predict elevated LV filling pressure (sensitivity=0.82, specificity=0.94).
Conclusions: Global IVR SR by 2-dimensional speckle tracking is strongly dependent on left ventricular relaxation. Non-invasive examination of strain rate may have potential to evaluate diastolic function in HCM.
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