Reversed Apico-Basal Myocardial Relaxation Sequence During Exercise in Long QT Syndrome Mutations Carriers With History of Previous Cardiac Events.

BACKGROUND

Recent echocardiography studies in inherited long QT syndrome (LQTS) have shown left ventricular (LV) myocardial relaxation disturbances to follow markedly prolonged and dispersed mechanical contraction.

AIM

We used speckle-tracking echocardiography to assess disturbances in LV myocardial relaxation sequence during exercise and their relationship to symptoms.

METHODS

Forty seven LQTS patients (45 ± 15 years, 25 female and 20 symptomatic, LVEF: 65 ± 6%) and 35 controls underwent exercise echocardiogram using Bruce protocol. ECG and echo parameters were recorded at rest, peak exercise (p.e.) and recovery.

RESULTS

Between patients and controls there were no differences in age, gender, HR or LVEF. At p.e, patients had longer time to LV longitudinal E (tE) at all three LV segments; basal ( < 0.0001), mid- cavity ( = 0.03) and apical ( = 0.03) whereas at rest such difference was noted only at base ( = 0.0007). Patients showed reversed apico-basal relaxation sequence (ΔtE) with early relaxation onset occurring later at base than at apex, both at rest (49 ± 43 vs. -29 ± 19 ms, < 0.0001) and at p.e. (46 ± 38 vs. -40 ± 22 ms, < 0.0001), particularly in symptomatic patients (69 ± 44 vs. 32 ± 26, < 0.0007). ΔtE correlated with longer QTc interval, lower E and attenuated LV stroke volume.

CONCLUSION

LQTS patients show reversed longitudinal relaxation sequence, which worsens with exercise, particularly in those with previous cardiac events.