Abstract 2121: Myocardial Mechanical Dispersion Assessed by Strain Echocardiography Identifies High Risk Patients with Long QT Syndrome
Background: Long QT syndrome (LQTS) predisposes to life-threatening ventricular arrhythmias. Prolonged action potentials in LQTS may cause prolonged myocardial contraction which can be assessed by strain echocardiography. We hypothesized that myocardial mechanical dispersion can be assessed as heterogeneity in myocardial contraction duration and serve as a risk marker in LQTS patients.
Methods: We included 81 mutation carriers with genotyped LQTS and 20 healthy control subjects. 41 mutations carriers had a history of cardiac arrest or syncope and 40 were asymptomatic. Myocardial contraction duration was assessed as time from Q on ECG to peak strain. Standard deviation of contraction duration from the 6 basal LV segments was calculated as a marker of mechanical dispersion. Figure⇓ is demonstrating homogeneous contraction duration in a healthy person compared to mechanical dispersion in a LQTS patient.
Results: Contraction duration was prolonged in LQTS mutation carriers compared to healthy controls (430±50 vs. 350±30ms, p<0.001) and in symptomatic compared to asymptomatic carriers (440±50 vs. 410±40ms, p<0.01). Mechanical dispersion was more pronounced in symptomatic mutation carriers compared to asymptomatic (65±22 vs. 34±18ms, p<0.001). Mechanical dispersion was better related to severe arrhythmia than QTc (AUC by ROC analysis 0.89 vs. 0.71).
Conclusions: Mechanical dispersion of myocardial contraction assessed by strain echocardiography was increased in LQTS mutation carriers and was superior to QTc in identifying cardiac events. This novel method can be implemented in clinical routine and may improve the management of LQTS patients.