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

Background: The distribution and magnitude of left ventricular hypertrophy (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 systolic dyssynchrony in patients with HCM by Tissue Doppler Imaging (TDI) and to find any correlation between TDI data and syncope.
Methods: A total of 44 consecutive patients with HCM are recruited in the present study. .All patients, � �underwent complete clinical and echocardiographic evaluation including TDI . The following were measured in 6 different basal and 6 mid-myocardial segments: systolic peak velocity(Sm), early diastolic myocardial velocity (Em), pre-contraction time(Q-Sm) from beginning of Q-wave of ECG to the onset of Sm, total asynchrony index ,interventricular mechanical delay(difference in Q-Aortic valve opening and Q-Pulmonic valve opening) and maximum difference in time to peak systolic velocity between 2 of 12 segments(ΔPVI).
Results: TDI analysis in HCM subgroup with syncope showed both significant interventricular (36.72±26.26 vs 14.74±11.30 msec, P<0.001) and intraventricular delays(39.40±22.38 vs27.70±17.32 msec, P=0.07). The prevalence of LV systolic dyssynchrony was from 20.5% to 38.6% based on different methods. Patients with syncope had greater impairment of regional systolic and early diastolic function, remarkably lower Sm and Em velocities.
Conclusion: The impairment of inter and intraventricular systolic synchronicity is significantly related to syncope in patients with HCM.TDI analysis may be able to select subgroups of HCM patients at increasing risk of syncope and major cardiac events.