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Article Type

Original Study

Abstract

Objective The objective of this study was to assess right ventricular (RV) deformation response to exercise in hypertrophic cardiomyopathy (HCM) and its relationship with left ventricular (LV) function using vector velocity imaging (VVI). Background RV adaptive mechanisms to exercise in HCM are poorly understood. VVI is achieved through the combination of speckle tracking, mitral annulus motion, tissue-blood border detection, and the periodicity of the cardiac cycle using R-R intervals. It can measure different parameters of deformation and dyssynchrony of the regional myocardium. Patients and methods Resting and exercise echocardiography was performed in 40 HCM patients and 33 healthy control individuals. Longitudinal peak systolic strain (εsys ) and strain rate (SR sys , SR e , SR a ) of RV segments from the apical four-chamber view were used to evaluate RV functional reserve (stress-rest/rest). Similar parameters were quantified in LV wall segments. Intra-V dyssynchrony was defined as SD of TTP (measured from regional strain curves for each segment as time from the beginning of the Q wave to time to peak åsys ). Results In HCM and immediately after exertion, RV åsys and SR sys were significantly lower and RV dyssynchrony was greater compared with those in the control participants. A significant correlation was evident between exercise capacity and RV TTP-SD and RV SR sys . RV functional systolic reserve showed a direct relationship with LV systolic functional reserve. However, using multivariate regression analysis, LV SR sys , and LV, TTP-SD is the only predictor of exercise capacity, whereas the RV functional reserve did not alter the outcome. Exercise stress-induced RV dysfunction in HCM is associated with exercise intolerance and strongly related to LV deformation abnormalities as evaluated by VVI. Conclusion Although exercise-induced RV dysfunction assessed during stress was statistically associated with exercise capacity, it was found that the LV systolic SR and systolic dyssynchrony at rest are major determinants of exercise tolerance in HCM.

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