Síndrome QT largo congenito

 Abstract in English, Spanish

Congenital long QT syndrome (LQTS) represents a group of heart diseases of genetic origin characterized by prolongation of the QT interval and an abnormal T wave on the electrocardiogram (ECG). They can have a dominant or recessive expression, the latter associated with sensorineural deafness. In both cases, its clinical presentation is associated with recurrent syncope and sudden death as a consequence of ventricular tachycardia, specifically Torsades de Pointes. Currently they are classified according to the specific genetic defect, being able to compromise around 16 genes and almost 2000 mutations. It should be suspected in individuals with related symptoms, electrocardiographic findings, and family history. Management is based on the reduction or elimination of symptoms, and concomitantly the prevention of sudden death (SD), in those children with congenital deafness, the management requires the application of the otolaryngologist specialist's own measures. The cardiovascular management implies the modification of lifestyles, mainly the prohibition of competitive sports, including swimming, avoiding exposure to loud sounds or triggers. The medications used include beta-blockers, and more rarely flecainide, ranozaline, and verapamil; invasive management consists of the implantation of a cardioverter defibrillator or even left sympathetic denervation, each with its own risks and benefits. In any of the cases, we must avoid the circumstances that increase the QT interval, as well as carry out the appropriate analysis of the benefits and risks of each possible invasive measure.

Keywords: Death, Sudden; Long QT Syndrome; Pediatrics; Torsades de Pointes.*1

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Abstract

Long QT syndrome (LQTS) is a rare cardiac channelopathy associated with syncope and sudden death due to torsades de pointes and ventricular fibrillation. Syncope and sudden death are frequently associated with physical and emotional stress. Management of patients with LQTS consists of life-style modification, β-blockers, left cardiac sympathetic denervation (LCSD), and implantable cardioverter-defibrillator (ICD) implantation. Prohibition of competitive exercise and avoidance of QT-prolonging drugs are important issues in life-style modification. Although β-blockers are the primary treatment modality for patients with LQTS, these drugs are not completely effective in some patients. Lifelong ICD implantation in young and active patients is associated with significant complications. LCSD is a relatively simple and highly effective surgical procedure. However, LCSD is rarely used.

Keywords: Adrenergic beta-blocker; Defibrillators, implantable; Long QT syndrome; Sympathectomy.

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Conflict of interest statement

The authors have no financial conflicts of interest.*2

Abstract

Objectives: This study sought to report our single-center experience with left cardiac sympathetic denervation (LCSD) for long QT syndrome (LQTS) since 1973.

Background: LCSD is still underutilized because clinicians are often uncertain whether to use it versus an implantable cardioverter-defibrillator (ICD).

Methods: We performed LCSD in 125 patients with LQTS (58% women, mean QT interval corrected for frequency [QTc] 527 ± 60 ms, 90% on beta blockers) with a follow-up of 12.9 ± 10.3 years. They were retrospectively divided into 4 groups according to the clinical/genetic status: very high risk (n = 18, symptomatic in the first year of life or with highly malignant genetics), with aborted cardiac arrest (ACA) (n = 31), with syncope and/or ICD shocks on beta blockers (n = 45), in primary prevention (n = 31).

Results: After LCSD, 17% in the very high risk group remained asymptomatic, compared with 52%, 47%, and 97% in the other 3 groups (P < 0.0001), with an overall 86% decrease in the mean yearly cardiac event rate (P < 0.0001). Among 45 patients with only syncope/ICD shocks before LCSD, none had ACA/sudden death as first symptom after LCSD and a 6-month post-LCSD QTc <500 ms predicted excellent outcome. Patients with a QTc ≥500 ms have a 50% chance of shortening it by an average of 60 ms. LCSD results are not affected by common genotypes.

Conclusions: We provide definitive evidence for the long-term efficacy of LCSD in LQTS. The degree of antiarrhythmic protection is influenced by patient's specificity and amount of QTc shortening. This novel approach to the analysis of the outcome allows cardiologists to rationally decide and tailor their management strategies to the individual features of their patients.

Keywords: cardiac sympathetic denervation; genetics; implantable cardioverter-defibrillator; long QT syndrome; sudden death; sympathetic nervous system.

Copyright © 2022 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.*3

Abstract

Long QT syndrome (LQTS) is a potentially life-threatening, but highly treatable genetic heart disease. LQTS-directed therapies often consist of beta-blockers (BBs), left cardiac sympathetic denervation (LCSD), and/or an implantable cardioverter defibrillator (ICD). However, in clinical practice, many patient-specific and genotype-directed permutations exist. Herein, we aim to review the spectrum of treatment configurations utilized at a single, tertiary center specializing in the care of patients with LQTS to demonstrate optimal LQTS-directed management is not amenable to a "one-size-fits-all" approach but instead benefits from patient- and genotype-tailored strategies.

Keywords: Genetic testing; Long QT syndrome; Precision therapy; Sudden cardiac death.

Copyright © 2022 Elsevier Inc. All rights reserved. *4

Abstract in English, Chinese

Objective: To investigate the long-term efficacy and safety of left cardiac sympathetic denervation(LCSD) for long QT syndrome(LQTS) patients with either recurrence on drug therapy intolerance/refusal. Methods: This study was a retrospective cohort study. The cases selected from 193 patients with LQTS who were enrolled in the Chinese Channelopathy Registry Study from November 1999 to November 2012. This study selected 28 LQTS patients with either recurrence on drug therapy intolerance/refusal and underwent LCSD surgery in the Peking University People's Hospital or Beijing Tongren Hospital. The patients were allocated into 3 groups: high-risk group(n=13, baseline QTc ≥550 ms or symptomatic in the first year of life or highly malignant genetics); intermediate-risk group(n=10, 500 ms≤baseline QTc<550 ms, symptomatic after the first year and without highly malignant genetics); low-risk group(n=5, baseline QTc<500 ms, symptomatic after the first year and without highly malignant genetics). LCSD was performed with the traditional supraclavicular approach or video assisted thoracoscopic surgery (VATS). Patients were regularly followed up until 20 years after the surgery. Data were collected before and 1 year after surgery and at the last follow-up. Patients' electrocardiograph(ECG), cardiac events and surgery-related complications were recorded. Kaplan-Meier survival analysis was used to determine the cardiac event-free survival based on different risk stratification and genotypes. Results: A total of 28 LQTS patients, aged 20.5 (15.0, 37.5) and underwent LCSD surgery, were enrolled in this study, including 23(82.1%) women. There were 11(39.3%) patients treated with traditional approach while 17(60.7%) with VATS-LCSD. There were 19(67.9%) patients had positive genetic test results, including 4 LQT1, 12 LQT2, 1 LQT1/LQT2 mixed type, and 2 Jervell-Lange-Nielsen (JLN) syndrome. The median follow-up period was 189.3(138.7, 204.9) months. The dropout rate was 10.7%(3/28) while 3 patients in the intermediate-risk group were lost to follow-up. Horner syndrome occurred in 1 patient (in the high-risk group). Sudden cardiac deaths were observed in 3 (12.0%) patients (all in the high-risk group), and 12 patients (48.0%) had syncope recurrences (2 in low-risk group, 3 in intermediate-risk group and 7 in high-risk group). A significant reduction in the mean yearly episodes of cardiac events was observed, from (3.5±3.3) before LCSD to(0.2±0.1) at one year after LCSD and (0.5±0.8) at last follow up(P<0.001). The mean QTc was shortened from (545.7±51.2)ms before the surgery to (489.0±40.1)ms at the last follow-up (P<0.001). Among the 20 patients with basic QTc ≥500 ms and completing the follow-up, the QTc intervals of 11(55.0%) patients were shortened to below 500 ms. The event free survival rates for any cardiac events after LCSD decreased sequentially in the low-, intermediate- and high-risk groups, and the difference was statistically significant (χ²=7.24, log-rank P=0.026). No difference was found in the event free survival rates among LQT1, LQT2 and undefined gene patients (χ²=5.20, log-rank P>0.05). Conclusions: LCSD surgery can reduce the incidence of cardiac events and shorten the QTc interval in patients with LQTS after the long-term follow-up. LCSD surgery is effective and safe for patients with LQTS ineffective or intolerant to drug therapy. However, high-risk patients are still at a high risk of sudden death after surgery and should be actively monitored and protected by combined therapies.*5

*1Congenital long QT syndrome

[Article in Spanish]

Luis Alfredo Melgar Quicaño et al. Arch Peru Cardiol Cir Cardiovasc. 2021.

*2Management of Patients with Long QT Syndrome

Yongkeun Cho. Korean Circ J. 2016 Nov.

*3Left Cardiac Sympathetic Denervation for Long QT Syndrome: 50 Years' Experience Provides Guidance for Management

Veronica Dusi et al. JACC Clin Electrophysiol. 2022 Mar.

Free article

*4Precision therapy in congenital long QT syndrome

Raquel Neves et al. Trends Cardiovasc Med. 2024 Jan.

*5The long-term efficacy of left cardiac sympathetic denervation in long QT syndrome

[Article in Chinese]

X Li et al. Zhonghua Xin Xue Guan Bing Za Zhi. 2022.