Prolonged myocardial contraction duration assessed by tissue Doppler imaging was superior to QTc interval for identifying cardiac events in LQTS patients (AUC 0.77 vs 0.66).
Observational (n=93)
Does myocardial contraction duration and dispersion assessed by tissue Doppler imaging identify high-risk individuals for cardiac events in patients with long QT syndrome?
Myocardial contraction duration and dispersion assessed by tissue Doppler imaging are superior to QTc interval for identifying LQTS patients at high risk for cardiac events.
Effect estimate: AUC (95% CI 0.65-0.89)
Absolute Event Rate: 0.77% vs 0.66%
AIMS: The aim of this study was to investigate whether prolonged and dispersed myocardial contraction duration assessed by tissue Doppler imaging (TDI) may serve as risk markers for cardiac events (documented arrhythmia, syncope, and cardiac arrest) in patients with long QT syndrome (LQTS). METHODS AND RESULTS: Seventy-three patients with genetically confirmed LQTS (nine double- and 33 single-mutation carriers with previous cardiac events and 31 single-mutation carriers without events) were studied. Myocardial contraction duration was prolonged in each group of LQTS patients compared with 20 healthy controls (P < 0.001). Contraction duration was longer in single-mutation carriers with previous cardiac events compared with those without (0.46 +/- 0.06 vs. 0.40 +/- 0.06 s, P = 0.001). Prolonged contraction duration could better identify cardiac events compared with corrected QT (QTc) interval in single-mutation carriers area under curve by receiver-operating characteristic analysis 0.77 [95% confidence interval (95% CI) 0.65-0.89 vs. 0.66 (95% CI 0.52-0.79)]. Dispersion of contraction was more pronounced in single-mutation carriers with cardiac events compared with those without (0.048 +/- 0.018 vs. 0.031 +/- 0.019 s, P = 0.001). CONCLUSION: Dispersion of myocardial contraction assessed by TDI was increased in LQTS patients. Prolonged contraction duration was superior to QTc for risk assessment. These new methods can easily be implemented in clinical routine and may improve clinical management of LQTS patients.
Haugaa et al. (2008) conducted an observational in Long QT syndrome (LQTS) (n=93). Tissue Doppler imaging (TDI) assessment of myocardial contraction duration vs. Corrected QT (QTc) interval was evaluated on Identification of cardiac events (documented arrhythmia, syncope, and cardiac arrest) (AUC, 95% CI 0.65-0.89). Prolonged myocardial contraction duration assessed by tissue Doppler imaging was superior to QTc interval for identifying cardiac events in LQTS patients (AUC 0.77 vs 0.66).
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