Left Ventricular Systolic Dyssynchrony in Patients with Hypertrophic Cardiomyopathy: The prevalence and its Relation to Syncope

Background: The distribution and magnitude of left ventricularhypertrophy (LVH) are not uniform in patients with hypertrophic cardiomyopathy (HCM) , which results in regional heterogeneity of left ventricular ( LV)systolic function. The aim of this study was to evaluate LV regional systolicdyssynchrony in patients with HCM by Tissue Doppler Imaging (TDI) and to findany correlation between TDI data and syncope.Methods: A total of 44 consecutive patients with HCM are recruited inthe present study. .All patients, underwent complete clinical andechocardiographic evaluation including TDI . The following were measured in 6different basal and 6 mid-myocardial segments: systolic peak velocity(Sm),early diastolic myocardial velocity (Em), pre-contraction time(Q-Sm) frombeginning of Q- wave of ECG to the onset of Sm, total asynchrony index,interventricular mechanical delay(difference in Q-Aortic valve opening andQ-Pulmonic valve opening) and maximum difference in time to peak systolicvelocity between 2 of 12 segments(ΔPVI).Results: TDI analysis in HCM subgroup with syncope showed bothsignificant interventricular (36.72±26.26 vs 14.74±11.30 msec, P<0.001) andintraventricular delays(39.40±22.38 vs27.70±17.32 msec, P=0.07). The prevalenceof LV systolic dyssynchrony was from 20.5% to 38.6% based on different methods.Patients with syncope had greater impairment of regional systolic and earlydiastolic function, remarkably lower Sm and Em velocities.Conclusion: The impairment of inter and intraventricular systolicsynchronicity is significantly related to syncope in patients with HCM.TDIanalysis may be able to select subgroups of HCM patients at increasing risk ofsyncope and major cardiac events