Characterization of Left Atrial Mechanics in Hypertrophic Cardiomyopathy and Essential Hypertension Using Vector Velocity Imaging.

Abstract

Systemic hypertension (HTN) and hypertrophic cardiomyopathy (HCM) may be associated with left atrial (LA) dilation, but whether LA functional abnormalities are characteristic to each disease or not, is unknown. The aim of this study was to characterize LA mechanical changes in patients with HTN and HCM using vector velocity imaging (VVI). VVI-derived longitudinal LA function was acquired from apical views in 76 CM patients, 33 hypertension patients and 30 age-matched controls. Peak atrial longitudinal strain (ɛsys ), atrial strain rate during systole (SRsys ), early diastole (SRe ), and late diastole (SRa ) were measured (corresponding to LA reservoir, conduit and contractile functions, respectively). Similar parameters were used to assess left ventricular (LV) function. LV mass and LA volume index were higher in HCM and HTN than in controls. Both LA Reservoir function (LA ɛsys SRsys ) and conduit function (SRe ) were more declined in HCM patients, in comparison to HTN patients and controls (P < 0.0001),whereas conduit function was the only function deteriorated in the HTN group. LA contractile function was preserved among patient groups. In HCM, LV ɛsys and SRa [P < 0.001] are independent predictors for LA ɛsys . While in hypertension, only LVMI is an independent predictor for LA dysfunction (P < 0.01). By receiver operating characteristic analyses, only atrial reservoir function was extrapolative and appeared to be accurate in discriminating HCM from both hypertension and controls, with LA ɛsys ≤ 33% being more sensitive (71.8%) and specific (75%). Response of LA mechanics to pathologic hypertrophy is entirely different. In HCM LA reservoir and conduit functions are more deteriorated and related to the severity of phenotype, while in hypertension the conduit function is chiefly affected and LA dysfunction is linked to a more advanced disease.