Abstract 1828: Predictive Value of T wave Morphology in LQT2 Patients with Borderline QTc Duration
Background: Long QT syndrome patients with type 2 disorder (LQT2) show QTc prolongation and changes in T wave morphology consisting of flat, low-amplitude and notched T waves. This study aimed to evaluate the prognostic significance of T wave morphology in LQT2 patients for predicting cardiac events.
Methods: Study population consisted of 405 genetically confirmed carriers of LQT2 gene mutations with QTc ≥440 ms (mean age: 26 years). Baseline ECGs were used to evaluate QTc duration and T wave morphology using classification adopted by the study and differentiating T waves as normal or abnormal (flat, broad upsloping, notched). The association between T wave morphology and endpoints, defined as aborted cardiac arrest or death, was tested separately in patients with borderline QTc (440–500ms) and in patients with definitely prolonged QTc (>500ms).
Results: Abnormal T wave morphology was observed in 37% of 281 patients with borderline QTc (440–500 ms) and in 50% of 124 patients with definitely prolonged QTc (>500 ms). Cox regression analysis revealed that, in LQT2 patients with borderline QTc, presence of T wave abnormalities was associated with significantly increased risk of aborted cardiac arrest or death (HR=4.10; p=0.005). The analysis of 124 patients with QTc>500 showed no significant association between T wave abnormalities and cardiac events (HR=0.69; p=0.446).
Conclusions: T wave abnormalities consisting of flat, broad based, or notched T waves indicate an increased risk of aborted cardiac arrest or death in LQT2 patients with borderline QTc. In LQT2 patients with definitely prolonged QTc, T wave abnormality does not improve risk stratification.