A Potential Diagnostic Approach for Foetal Long-QT Syndrome, Developed and Validated in Children

Fetal Long QT Syndrome - Challenges in Perinatal Management: A Review and Case Report. Induction of Labor and Vaginal Birth Under Continuous Magnesium Therapy

Congenital LQTS is an often undetected inherited cardiac channel dysfunction and can be a reason for intrauterine fetal demise. It can present in utero as CTG and ultrasound abnormalities, i. e., bradycardia, ventricular tachycardia, or fetal hydrops. Diagnosis is made by CTG, echocardiography, or fMCG. Intrauterine therapy with a ß blocker and i. v. magnesium should be started. Our objective was to examine the current knowledge about diagnosis and treatment of LQTS and in particular to highlight the opportunity of vaginal birth under continuous intravenous magnesium therapy. Therefore, a thorough MEDLINE and Google Scholar search was conducted. Randomized controlled trials, meta-analyses, prospective and retrospective cohort trials, and case reports were considered. We showed the possibility of vaginal delivery under continuous magnesium therapy in a case of suspected fetal LQTS. A stepwise concept for diagnosis, monitoring, and peripartum management in low, intermediate, and high risk cases of fetal LQTS is presented. If risk is low or intermediate, a vaginal delivery under continuous monitoring is reasonable. Induction of labor at term should be evaluated.

Congenital long QT syndrome: A challenging diagnosis by fetal echocardiography

The diagnosis of long QT syndrome (LQTS) in utero presents many challenges for clinicians, and there is high risk for intrauterine fetal demise as life-threatening arrhythmias develop secondary to QT prolongation. We describe a challenging case of a fetus presenting with sinus bradycardia and second-degree atrioventricular block with episodes of ventricular tachycardia. A prenatal diagnosis of LQTS was suspected given the fetal echocardiographic findings of a short ventricular relaxation time, due to extremely prolonged refractory period. The patient was delivered emergently due to Torsade's with hydrops, with ongoing arrhythmia despite medical management requiring implantation of pacemaker and sympathectomy. Early recognition of LQTS is important to optimize fetal survival with prompt medical management.

Left Ventricular Contraction Duration Is the Most Powerful Predictor of Cardiac Events in LQTS: A Systematic Review and Meta-Analysis

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 (QT_C), QT_C 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—QT_C, WMD 72.8; QT_C 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 QT_C 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.