Key result
Left ventricular contraction duration ≥430 ms strongly predicted cardiac events in LQTS patients, demonstrating a sensitivity of 71%, specificity of 84%, and a diagnostic odds ratio >19.5.
Why the study?
Prolonged left ventricular contraction was identified as a potential risk for arrhythmia in LQTS, but the best electromechanical predictor for cardiac events remained unclear.
Do electromechanical echocardiographic indices, specifically left ventricular contraction duration, predict cardiac events in patients with Long-QT syndrome?
Meta-Analysis (n=1,414)
Do electromechanical echocardiographic indices, specifically left ventricular contraction duration, predict cardiac events in patients with Long-QT syndrome?
Prolonged left ventricular contraction duration (≥430 ms) is a powerful echocardiographic predictor of cardiac events in patients with Long-QT syndrome, outperforming traditional electrical indices.
May aid LQTS risk stratification via LV contraction duration; extends mechanical echo assessment beyond electrical indices.
Background: Long-QT syndrome (LQTS) is primarily an electrical disorder characterized by a prolonged myocardial action potential. The delay in cardiac repolarization leads to electromechanical (EM) abnormalities, which adds a diagnostic value for LQTS. Prolonged left ventricular (LV) contraction was identified as a potential risk for arrhythmia. The aim of this meta-analysis was to assess the best predictor of all EM parameters for cardiac events (CEs) in LQTS patients. Methods: We systematically searched all electronic databases up to March 2020, to select studies that assessed the relationship between echocardiographic indices—contraction duration (CD), mechanical dispersion (MD), QRS onset to peak systolic strain (QAoC), and the EM window (EMW); and electrical indices— corrected QT interval (QTC), QTC dispersion, RR interval in relation to CEs in LQTS. This meta-analysis included a total of 1041 patients and 373 controls recruited from 12 studies. Results: The meta-analysis showed that LQTS patients had electrical and mechanical abnormalities as compared to controls—QTC, WMD 72.8; QTC dispersion, WMD 31.7; RR interval, WMD 91.5; CD, WMD 49.2; MD, WMD 15.9; QAoC, WMD 27.8; and EMW, WMD −62.4. These mechanical abnormalities were more profound in symptomatic compared to asymptomatic patients in whom disturbances were already manifest, compared to controls. A CD ≥430 ms had a summary sensitivity (SS) of 71%, specificity of 84%, and diagnostic odds ratio (DOR) >19.5 in predicting CEs. EMW and QTC had a lower accuracy. Conclusions: LQTS is associated with pronounced EM abnormalities, particularly prolonged LV myocardial CD, which is profound in symptomatic patients. These findings highlight the significant role of EM indices like CD in managing LQTS patients.
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Abdelsayed et al. (2020) conducted a meta-analysis in Long-QT syndrome (LQTS) (n=1,414). Left ventricular contraction duration (CD) ≥430 ms vs. Controls was evaluated on Cardiac events (CEs) (DOR >19.5). Left ventricular contraction duration ≥430 ms strongly predicted cardiac events in LQTS patients, demonstrating a sensitivity of 71%, specificity of 84%, and a diagnostic odds ratio >19.5.
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