الفهرس 
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Abstract
Objectives: The impairment of left atrial mechanics (LA) is previously described in hypertrophic cardiomyopathy (HCM). It is independently influenced by left ventricular (LV) mechanics and correlated to the severity of LV phenotype. We examined the alterations in LA functions following surgical septal myectomy using vector velocity imaging (VVI).
Methods: Twenty-five HCM patients, 60% males with mean age (34.5±12 years) were investigated before and six months after surgical myectomy using VVI. In addition to LA size and volume index (LAD, LAVI), LA reservoir function using peak systolic strain (εsys) & systolic strain rate (SRsys), LA conduit (SRe) and LA contractile (SRa) functions were analyzed. Electrophysiologic properties of the LA were investigated using difference between time to peak SRa (TTP-d) and the standard deviation (SD) of TTP-mean derived from regional SR curves. their (Δ) changes were calculated. Similar parameters were quantified in LV (LV εsys) and right ventricle (RV εsys) from apical views.
Results: Despite, all study patients demonstrated atrial reverse remodeling post myectomy, 17(68%) of HCM patients showed normalization of LAVI. All patients showed reduction of LVOT gradient to below 20 mmHg, reduction of septal thickness, LV mass index and severity of mitral regurgitation and improvement of their functional class from NYHA class III to class I. Although there was significant reduction of LV (LV εsys :12.2±3.4 to 9.2±1.8 P<0.001, EF% : from 73.6±10.7 to 68.2±5.3, P<0.03 ) and RV ( εsys : from P<0.04) systolic mechanics, respectively following myectomy, there were significant, increase in LA reservoir function (εsys: 26 ± 13vs 31 ± 16%, P<.03, SRsys: 0.9 ± 0.4vs 1.2 ± 0.5%s-1, P<0.02) and contractile function (SRa: -0.8 ± 0.4vs -1.2 ± 0.9s-1, P<0.04) respectively.
Furthermore, LA contractile function become more homogenonous (LA TTP-SD: from all echocardiographic parameters LV global strain 13.7 ± 3.2 versus 11.2 ± 3.6, P<0.029. RV global strain 13.4 ± 3.4versus 9.4 ± 4.7, P<0.026 differentiate patients with normalized LAVI following myectomy.Surgical myectomy is associated with improvement of LA mechanical properties and reverse remolding in HCM patient with symptomatic improvement despite subclinical reduction of LV and RV systolic mechanics.