الفهرس 
1- ReviewOnly 14 pages are availabe for public view
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Abstract
Background: Hypertrophic cardiomyopathy (HCM) is usually associated
with ECG abnormalities. QT interval and its dispersion can be clinical
markers of electrophysiologic instability and ventricular arrhythmias.
Objectives: We aimed to clarify the relation of QT variables to
mechanical dyssynchrony and myocardial function in HCM.
Methods: The study population comprised 82 HCM patients, 28 healthy
subjects as control. We assessed regional deformation indexes using
Vector Velocity Imaging (VVI) in 12 myocardial segments. Peak systolic
strain (εsys), strain rate [SRsys] and post systolic strain (PSS) were
measured. Contraction time (CT) was measured from regional strain
curves for each segment, as time from beginning of Q wave to time to
peak εsys (TPS), mechanical dyssynchrony was estimated as TPS‐SD. from
12‐lead surface ECG, QT interval, QT dispersion and its corrected values
were measured.
Results: According to QTc (QTc≥ or < 440 ms), patients were categorized
into 2 groups: Long QT and normal QT HCM. In long QT group, QTcd and
CT in all LV segments were significantly prolonged, εsys and SRsys were
markedly attenuated compared with the other two groups (P<0.001). LV
dyssynchrony was significantly greater (P<0.001) and PSS was more
frequent in long QT HCM compared to the other two groups (P<0.001).
TPS‐SD was correlated positively with QTc (r=.38,P<0.01) and QTcd
(r=0.45,P<0.001). QTc≥ 440 ms identified LV mechanical dysynchrony
with 70% sensitivity, 100% specificity and positive predictive value.