Abstract 16271: Transmural Dispersion of Myocardial Contraction in Patients With Long QT Syndrome 2 and Jervell and Lange-Nielsen Syndrome
Introduction: LQTS is characterized by prolonged myocardial action potential duration (APD). The longest APD is reported in the endo- and mid-myocardium. Prolonged APD in LQTS may cause prolonged cardiac contraction which can be assessed by strain echocardiography. We hypothesized that myocardial contraction is most prolonged in subendocardial myofibers in LQTS patients and that inhomogeneous transmural contraction is related to risk of spontaneous arrhythmia.
Methods: We included 99 genotyped LQTS mutation carriers (64 LQT1, 26 LQT2 and 9 with Jervell and Lange-Nielsen syndrome) and 35 healthy individuals. A history of cardiac arrhythmias (syncope or documented ventricular arrhythmia) was present in 47 mutations carriers and 52 were asymptomatic. Myocardial contraction duration was assessed by strain echocardiography as time from ECG Q to peak strain in 16 LV segments. Strain was assessed along the longitudinal axis, representing subendocardial fibers and along the circumferential axis, representing mid-myocardial fibers.
Results: Contraction duration by longitudinal strain was longer than by circumferential strain in symptomatic LQTS patients (460±45ms vs. 440±45ms, p<0.05) (Figure) indicating transmural mechanical dispersion. This difference was not present in asymptomatic patients and healthy. The most prominent time differences were found in septal and anterior segments in LQT2 and patients with Jervell and Lange-Nielsen syndrome (445±65ms vs. 400±45ms, p=0.01and 500±60ms vs. 410±55, p=0.01).
Conclusions: Contraction duration in symptomatic LQTS mutation carriers was longer in the subendocardium than in the mid-myocardium, indicating transmural mechanical dispersion which was not present in asymptomatic and healthy individuals. Transmural mechanical dispersion was particularly pronounced in patients with LQT2 and Jervell and Lange-Nielsen syndrome.
- © 2010 by American Heart Association, Inc.