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Left ventricular mechanical dispersion by tissue Doppler imaging: a novel approach for identifying high-risk
Kristina Hermann Haugaa1, Thor Edvardsen, Trond P Leren
1Department of Cardiology, Rikshospitalet University Hospital, University of Oslo, N-0027 Oslo, Norway.
Insights
Prolonged myocardial contraction duration, measured by tissue Doppler imaging (TDI), is a superior risk marker for cardiac events in long QT syndrome (LQTS) patients compared to the corrected QT (QTc) interval.
Area of Science:
- Cardiology
- Medical Imaging
- Genetics
Background:
- Long QT syndrome (LQTS) is a genetic disorder associated with increased risk of cardiac events.
- Current risk stratification methods, such as the corrected QT (QTc) interval, have limitations in identifying high-risk individuals.
- Tissue Doppler imaging (TDI) offers novel parameters for assessing myocardial function.
Purpose of the Study:
- To evaluate if prolonged and dispersed myocardial contraction duration, assessed by TDI, can serve as risk markers for cardiac events in LQTS patients.
- To compare the predictive value of myocardial contraction duration with the QTc interval for cardiac events in LQTS.
Main Methods:
- Seventy-three genetically confirmed LQTS patients and 20 healthy controls were studied.
- Myocardial contraction duration and dispersion were measured using TDI.
- Cardiac events included documented arrhythmia, syncope, and cardiac arrest.
- Receiver-operating characteristic (ROC) analysis was used to compare the predictive accuracy of contraction duration and QTc interval.
Main Results:
- Myocardial contraction duration was significantly prolonged in all LQTS patient groups compared to controls (P < 0.001).
- Single-mutation LQTS carriers with previous cardiac events had longer contraction duration (0.46 ± 0.06 s) than those without events (0.40 ± 0.06 s, P = 0.001).
- Prolonged contraction duration demonstrated superior risk identification for cardiac events compared to QTc interval in single-mutation carriers (AUC 0.77 vs. 0.66).
- Dispersion of contraction was more pronounced in LQTS patients with a history of cardiac events (P = 0.001).
Conclusions:
- Dispersion of myocardial contraction is increased in LQTS patients.
- Prolonged myocardial contraction duration is a more effective risk assessment tool than QTc interval for LQTS.
- TDI-based assessment of myocardial contraction offers a promising, easily implementable method to improve clinical management of LQTS patients.
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.
