International Cohort of Neonatal Timothy Syndrome.

INTRODUCTION: Timothy syndrome (TS) is an extremely rare, multisystem disorder classically associated with long QT, syndactyly, ventricular arrhythmias, and hypoglycaemia. A neonatal diagnosis allows maximal medical and device therapy to be implemented to avoid malignant arrhythmias and sudden cardiac death. METHODS: This was a retrospective case series study of type I TS (TS1) patients using data from the Timothy Syndrome Foundation's international registry, encompassing patients with a genetic diagnosis (CACNA1C variant G406R in exon 8A) recruited over a 28-year period. RESULTS: Forty-four cases of TS1 were included (26 male; 60%). Mean gestational age (GA) was 35.6 weeks (range 28 weeks - term), with 43% of patients born less than 37 weeks GA. In TS1 patients presenting with foetal bradycardia, mean GA was significantly lower (34.2 weeks, p < 0.05). Foetal bradycardia secondary to atrioventricular block was present in 20 patients (45%), resulting in premature delivery in 14 patients (32%). Fifteen patients (34%) were diagnosed with TS1 as neonates. Long QT at birth helped secure a diagnosis in 25 patients (57%). Syndactyly was seen in most patients (n = 40, 91%). Twenty patients died, with an average age of death of 2.3 years (range 1 month-6 years). Of the 7 patients who died before the first year of life (16%), the average age of death was 2.5 months. CONCLUSION: TS is associated with high early mortality. TS should be considered in paediatric patients presenting with long QT and syndactyly. Recognition of TS in the neonatal period allows for early intervention to prevent life-threatening arrhythmias.

QT interval prolongation and the risk of malignant ventricular dysrhythmia and/or cardiac arrest: Systematic search and narrative review of risk related to the magnitude of QT interval length.

Prolongation of the QTc interval is associated with an increased risk of malignant ventricular dysrhythmias, such as ventricular tachycardia (VT), and sudden cardiac death. The quantifiable risk rates of adverse dysrhythmic outcome in relation to specific QTc interval length are not known. We conducted a literature review on the topic of QT interval prolongation in adult patients and the associated risk of malignant dysrhythmic event. We specifically formulated our literature search and subsequent literature review to address the following question: Can the clinician identify specific QTc intervals at which a specific quantifiable risk of malignant dysrhythmic event (malignant ventricular dysrhythmia and/or cardiac arrest) occurs in an undifferentiated adult patient population? In the literature search, we identified 701 studies; upon review using specific, pre-determined inclusion criteria, we identified 16 articles for inclusion in the review. From this literature, we were unable to answer the question in a quantifiable manner and only noted that the risk of malignant dysrhythmic event increases with progressively longer QTc interval. The current literature on this topic is inadequate to answer this important question due to heterogenous study methodology, patient populations, endpoints, and periods of observation. Additional prospective research is required on this topic, aimed at addressing the important issue of specific, quantifiable risk and its relation to degree of prolongation of the QTc interval.

Identification of important risk factors for all-cause mortality of acquired long QT syndrome patients using random survival forests and non-negative matrix factorization.

BACKGROUND: Acquired long QT syndrome (aLQTS) is often associated with poor clinical outcomes. OBJECTIVE: The purpose of this study was to examine the important predictors of all-cause mortality of aLQTS patients by applying both random survival forest (RSF) and non-negative matrix factorization (NMF) analyses. METHODS: Clinical characteristics and manually measured electrocardiographic (ECG) parameters were initially entered into the RSF model. Subsequently, latent variables identified using NMF were entered into the RSF as additional variables. The primary outcome was all-cause mortality. RESULTS: A total of 327 aLQTS patients were included. The RSF model identified 16 predictive factors with positive variable importance values: cancer, potassium, RR interval, calcium, age, JT interval, diabetes mellitus, QRS duration, QTp interval, chronic kidney disease, QTc interval, hypertension, QT interval, female, JTc interval, and cerebral hemorrhage. Increasing the number of latent features between ECG indices, which incorporated from n = 0 to n = 4 by NMF, maximally improved the prediction ability of the RSF-NMF model (C-statistic 0.77 vs 0.89). CONCLUSION: Cancer and serum potassium and calcium levels can predict all-cause mortality of aLQTS patients, as can ECG indicators including JTc and QRS. The present RSF-NMF model significantly improved mortality prediction.

Complex and Novel Arrhythmias Precede Stillbirth in Fetuses With De Novo Long QT Syndrome.

BACKGROUND: Long QT syndrome (LQTS) is a leading cause of sudden cardiac death in early life and has been implicated in ≈10% of sudden infant deaths and unexplained stillbirths. The purpose of our study was to use fetal magnetocardiography to characterize the electrophysiology and rhythm phenotypes of fetuses with de novo and inherited LQTS variants and identify risk factors for sudden death before birth. METHODS: We reviewed the fetal magnetocardiography database from the University of Wisconsin Biomagnetism Laboratory for fetuses with confirmed LQTS. We assessed waveform intervals, heart rate, and rhythm, including the signature LQTS rhythms: functional 2° atrioventricular block, T-wave alternans, and torsade de pointes (TdP). RESULTS: Thirty-nine fetuses had pathogenic variants in LQTS genes: 27 carried the family variant, 11 had de novo variants, and 1 was indeterminate. De novo variants, especially de novo SCN5A variants, were strongly associated with a severe rhythm phenotype and perinatal death: 9 (82%) showed signature LQTS rhythms, 6 (55%) showed TdP, 5 (45%) were stillborn, and 1 (9%) died in infancy. Those that died exhibited novel fetal rhythms, including atrioventricular block with 3:1 conduction ratio, QRS alternans in 2:1 atrioventricular block, long-cycle length TdP, and slow monomorphic ventricular tachycardia. Premature ventricular contractions were also strongly associated with TdP and perinatal death. Fetuses with familial variants showed a lower incidence of signature LQTS rhythm (6/27=22%), including TdP (3/27=11%). All were live born. CONCLUSIONS: The malignancy of de novo LQTS variants was remarkably high and demonstrate that these mutations are a significant cause of stillbirth. Their ability to manifest rhythms not known to be associated with LQTS increases the difficulty of echocardiographic diagnosis and decreases the likelihood that a resultant fetal loss is attributed to LQTS. Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT03047161.

Left cardiac sympathetic denervation in the management of long QT syndrome and catecholaminergic polymorphic ventricular tachycardia: A meta-regression.

BACKGROUND: Left cardiac sympathetic denervation (LCSD) has been proposed as useful therapy for long QT syndrome (LQTS) and catecholaminergic polymorphic ventricular tachycardia (CPVT), in addition to anti-arrhythmic agents and implantable cardioverter defibrillators. This study aimed to assess the current evidence for LCSD and compare the open vs the video-assisted thoracoscopic surgery (VATS) approaches. METHODS: MEDLINE, Embase and Cochrane library databases were searched up to December 2018 for studies reporting the long-term outcomes of LCSD in LQTS, CPVT patients. The incidence of cardiac events (CEs) before and after surgery, the change in QTc interval, and surgical complications were pooled to estimate the efficacy of LCSD. Meta-regression was used to estimate the effects of surgical approach (open vs VATS) on outcomes following LCSD. RESULTS: Twenty-seven papers met our inclusion criteria (647 patients). VATS was used in 408 patients (63.1%), open surgery in 239 (36.9%). Mean follow-up was 32.3 ± 32.5 months. Postsurgery, 398/585 patients (68.0%) were free of CEs and QTc decreased from 522 ± 61.6 ms to 494 ± 52.3 ms. Meta-regression showed no differences between the two approaches in the incidence of CEs and surgical complications. VATS was associated with a smaller reduction in QTc (ß-coefficient -20.04, 95% CI -36.82 to -3.27, P = .019). CONCLUSIONS: LCSD was associated with a reduction in the incidence of CEs in LQTS, CPVT patients and in the duration of QTc. Open surgery was associated with a greater reduction in QTc. Due to the limitations that hindered our study, a randomized trial is warranted to fully establish LCSD safety and efficacy.

[Analysis of 30 cases of inherited cardiac arrhythmia syndrome in children].

Objective: To analyze and summarize the diagnosis and treatment experience of common inherited cardiac arrhythmia syndrome in pediatric patients, and explore the most appropriate therapy. Methods: A retrospective review identified 30 pediatric cases (19 males, 11 females) diagnosed with long QT syndrome (LQTS), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), hypertrophic cardiomyopathy (HCM), arrhythmogenc right ventricular cardiomyopathy (ARVC) from January 2008 to December 2018 in the Pediatric Cardiology Department, Guangdong Provincial People's Hospital. Data obtained included the diagnosis, treatment and follow-up outcome. Results: The most common inherited cardiac arrhythmia syndromes were LQTS (n=14) including 1 case with epilepsy, CPVT (n=5), HCM (n=7), ARVC (n=1), and BrS (n=3). Twenty-seven cases were admitted to hospital due to syncope, whereas the remaining 3 cases of BrS had not presented with syncope before admission. The average onset age of inherited arrhythmia was (10.0±3.3) years. Genetic testing was performed on 20 patients. The median follow-up time was 40 months. Among 15 patients who underwent implantable cardioverter defibrillator (ICD) and survived, 2 patients had frequent ICD discharge. One patient underwent radiofrequency ablation, and the other one received left cardiac sympathetic denervation and an increased ICD defibrillation threshold, and the number of ICD discharge was significantly reduced. Among 10 patients who received drug therapy, 4 patients including two patients who discontinued treatment without advices died. Two patients whose parents refused treatment died, 1 case diagnosed with unexplained sudden cerebral death, and the remaining 2 cases without indication for drug therapy survived without any treatment. Conclusions: Mortality rate is high in pediatric patients with inherited cardiac arrhythmia and syncope. The therapeutic effect of drugs are not satisfactory, ICD implantation is the most effective treatment to prevent sudden cardiac death currently, but the postoperative frequent discharge should be brought to the forefront and handled in time.

Clinical characterization of men with long QT syndrome and torsades de pointes associated with hypogonadism: A review and pharmacovigilance study.

BACKGROUND: Long QT syndrome (LQTS) can cause the potentially fatal ventricular tachycardia torsades de pointes (TdP). QT interval corrected for heart rate (QTc) is shorter in men than in women, with testosterone contributing to shorten QTc. We recently described male hypogonadism as a reversible risk factor for acquired LQTS and TdP, but the clinical characteristics of such patients have not been characterized. AIMS: To describe the clinical characteristics of men with acquired LQTS or TdP associated with hypogonadism caused by endocrine conditions or androgen deprivation therapy (ADT), and to evaluate the relationship between testosterone concentrations and electrocardiographic changes. METHODS: We searched MEDLINE (to 04 January 2019) and the French pharmacovigilance database (to 09 August 2018) to identify male cases of acquired LQTS and TdP associated with endocrine hypogonadism or ADT; their narratives were gathered from reporting collaborators. RESULTS: We identified seven cases of TdP (one fatal) with endocrine hypogonadism, abnormally long QTc and morphologically abnormal T-wave notches. After reversion of low testosterone concentrations in the surviving patients (N=6), QTc shortened, T-wave morphology normalized and there was no TdP recurrence. Among these cases, none had mutation in the LQTS genes, three men required testosterone and three had reversible hypogonadism after resolution of a concurrent acute severe illness. We found an additional 27 reports of men with LQTS (N=6), TdP (N=9; 2/9 fatal) or sudden death (N=12; 10/12 fatal) suspected to be induced or favoured by ADT (24/27 for prostate cancer). Generally, after ADT withdrawal, QTc shortened and no TdP recurred. CONCLUSION: We propose seeking for hypogonadism caused by endocrine conditions or ADT in men presenting with TdP. Caution is warranted when ADT is used in situations at risk of TdP. Testosterone may be useful to treat or prevent TdP.

Association between Use of Methadone, Other Central Nervous System Depressants, and QTc Interval-Prolonging Medications and Risk of Mortality in a Large Cohort of Women Living with or at Risk for Human Immunodeficiency Virus Infection.

STUDY OBJECTIVE: To evaluate the association between use of methadone, other central nervous system (CNS) depressants, and QTc interval-prolonging medications and risk of mortality among human immunodeficiency virus (HIV)-infected and at-risk HIV-uninfected women. DESIGN: Multicenter, prospective, observational cohort study (Women's Interagency HIV Study [WIHS]). PARTICIPANTS: A total of 4150 women enrolled in the WIHS study between 1994 and 2014 who were infected (3119 women) or not infected (1031 women) with HIV. MEASUREMENTS AND MAIN RESULTS: Data on medication utilization were collected from all study participants via interviewer-administered surveys at 6-month intervals (1994-2014). Mortality was confirmed by National Death Index data. With age defining the time scale for the analysis, Cox proportional hazards models were used to estimate hazard ratios (HRs) for all-cause mortality in HIV-infected and -uninfected women and non-acquired immunodeficiency syndrome (AIDS) deaths in HIV-infected women. A total of 1046 deaths were identified, of which 429 were considered non-AIDS deaths. Use of benzodiazepines, CNS depressants (excluding methadone), and number of medications with conditional QTc interval-prolonging effects were each associated with all-cause mortality in multivariate models of HIV-infected women: hazard ratio (HR) 1.28, 95% confidence interval (CI) 1.01-1.60, p=0.037; HR 1.61, 95% CI 1.35-1.92, p<0.0001; and HR 1.15 per drug, 95% CI 1.00-1.33, p=0.047, respectively. Other explanatory variables for all-cause mortality in this model included HIV viral load, CD4+  cell count, renal function, hemoglobin and albumin levels, HIV treatment era, employment status, existence of depressive symptoms, ever use of injection drugs, and tobacco smoking. Of interest, use of CNS depressants (excluding methadone) was also associated with non-AIDS deaths (HR 1.49, 95% CI 1.49-2.2, p<0.0001). Although use of benzodiazepines and conditional QT interval-prolonging medications were associated with increased risk of non-AIDS mortality (HR 1.32 and 1.25, respectively), the effect was not statistically significant (p>0.05). CONCLUSION: In this cohort of HIV-infected and at-risk HIV-uninfected women, use of benzodiazepines, CNS depressants, and conditional QTc interval-prolonging medications were associated with a higher risk of mortality independent of methadone and other well-recognized mortality risk factors. Care must be taken to assess risk when prescribing these medications in this underserved and at-risk patient population.

Significance of prolonged QTc in acute exacerbations of COPD requiring hospitalization.

Background: A prolonged QT interval is associated with increased risk of Torsade de Pointes and cardiovascular death. The prevalence and clinical relevance of QT prolongation in acute exacerbations of COPD (AECOPD), with high risk for cardiac morbidity and mortality, is currently unclear. Methods: A dual cross-sectional study strategy was therefore designed. A retrospective study evaluated 140 patients with an AECOPD requiring hospitalization, half of which had prolonged QTc on the admission ECG. Univariate and multivariate analyses were conducted to determine associated factors; Kaplan-Meier and Cox regression analyses to assess prognostic significance. A prospective study evaluated 180 pulmonary patients with acute respiratory problems requiring hospitalization, to determine whether a prolonged QTc at admission represents an AECOPD-specific finding and to investigate the change in QTc-duration during hospitalization. Results: Retrospectively, hypokalemia, cardiac troponin T and conductance abnormalities on ECG were significantly and independently associated with QTc prolongation. A prolonged QTc was associated with increased all-cause mortality (HR 2.698 (95% CI 1.032-7.055), p=0.043), however, this association was no longer significant when corrected for age, FEV1 and cardiac troponin T. Prospectively, QTc prolongation was observed in 1/3 of the patients diagnosed with either an AECOPD, lung cancer, pulmonary infection or miscellaneous acute pulmonary disease, and was not more prevalent in AECOPD. The QTc-duration decreased significantly during hospitalization in patients with and without COPD. Conclusion: A prolonged QTc is a marker of underlying cardiovascular disease during an AECOPD. It is not COPD-specific, but a common finding during the acute phase of a pulmonary disease requiring urgent hospital admission.

Increased long QT and torsade de pointes reporting on tamoxifen compared with aromatase inhibitors.

OBJECTIVE: A prolonged QTc (LQT) is a surrogate for the risk of torsade de pointes (TdP). QTc interval duration is influenced by sex hormones: oestradiol prolongs and testosterone shortens QTc. Drugs used in the treatment of breast cancer have divergent effects on hormonal status. METHODS: We performed a disproportionality analysis using the European database of suspected adverse drug reaction (ADR) reports to evaluate the reporting OR (ROR χ2) of LQT, TdP and ventricular arrhythmias associated with selective oestrogen receptor modulators (SERMs: tamoxifen and toremifene) as opposed to aromatase inhibitors (AIs: anastrozole, exemestane and letrozole). When the proportion of an ADR is greater in patients exposed to a drug (SERMs) compared with patients exposed to control drug (AIs), this suggests an association between the specific drug and the reaction and is a potential signal for safety. Clinical and demographic characterisation of patients with SERMs-induced LQT and ventricular arrhythmias was performed. RESULTS: SERMs were associated with higher proportion of LQT reports versus AIs (26/8318 vs 11/14851, ROR: 4.2 (2.11-8.55), p<0.001). SERMs were also associated with higher proportion of TdP and ventricular arrhythmia reports versus AIs (6/8318 vs 2/14851, ROR: 5.4 (1.29-26.15), p:0.02; 16/8318 vs 12/14851, ROR: 2.38 (1.15-4.94), p:0.02, respectively). Mortality was 38% in patients presenting ventricular arrhythmias associated with SERMs. CONCLUSIONS: SERMs are associated with more reports of drug-induced LQT, TdP and ventricular arrhythmias compared with AIs. This finding is consistent with oestradiol-like properties of SERMs on the heart as opposed to effects of oestrogen deprivation and testosterone increase induced by AIs. TRIAL REGISTRATION NUMBER: NCT03259711.

Acquired long QT syndrome in hospitalized patients.

BACKGROUND: Acquired long QT syndrome (ALQTS) has long been overlooked in clinical practice. Recent studies reported that severe ALQTS (QTc ≥500 ms) in hospitalized patients is associated with increased all-cause mortality. OBJECTIVE: The purpose of this study was to determine the role of ALQTS in the clinical outcomes of hospitalized patients. METHODS: Electronic medical records were reviewed to identify severe ALQTS in hospitalized patients in a single study center from September 1, 2013, to February 28, 2014. Up to 1-year follow-up was conducted in the ALQTS subjects and compared with age-, gender-, and admitting diagnosis-matched hospitalized patients with a normal QT interval. RESULTS: Severe ALQTS (QTc 529 ± 38 ms) was seen in 0.7% (293/41,649) of hospitalized patients, of whom 86% were treated in noncardiology departments. All-cause mortality was 32% in the ALQTS group vs 14% in the control group (P <.001) during follow-up of 255 ± 63 days. Syncope and life-threatening ventricular arrhythmia were more frequent in patients with severe ALQTS (6% vs 0.6%, P <.0001). Cerebral hemorrhage (odds ratio [OR] 6.405, 95% confidence interval [CI] 2.341-17.525), cancer (OR 5.937, 95% CI 2.658-13.260), infection (OR 2.207, 95% CI 1.124-4.333), and end-stage disease (OR 2.092, 95% CI 1.045-4.191) are the major contributors to all-cause mortality in ALQTS. CONCLUSION: Severe ALQTS is not uncommon in hospitalized patients. It can be easily overlooked because the majority of patients with severe ALQTS are treated in noncardiology departments. The clinical outcome of severe ALQTS is poor. Removing QT-prolonging factors may reduce the risks of fatal arrhythmia and sudden death in patients with ALQTS.

High-Dose Citalopram and Escitalopram and the Risk of Out-of-Hospital Death.

OBJECTIVE: Studies demonstrating that higher doses of citalopram (> 40 mg) and escitalopram (> 20 mg) prolong the corrected QT interval prompted regulatory agency warnings, which are controversial, given the absence of confirmatory clinical outcome studies. We compared the risk of potential arrhythmia-related deaths for high doses of these selective serotonin reuptake inhibitors (SSRIs) to that for equivalent doses of fluoxetine, paroxetine, and sertraline. METHODS: The Tennessee Medicaid retrospective cohort study included 54,220 persons 30-74 years of age without cancer or other life-threatening illness who were prescribed high-dose SSRIs from 1998 through 2011. The mean age was 47 years, and 76% were female. Demographic characteristics and comorbidity for individual SSRIs were comparable. Because arrhythmia-related deaths are typically sudden and occur outside the hospital, we analyzed out-of-hospital sudden unexpected death as well as sudden cardiac deaths, a more specific indicator of proarrhythmic effects. RESULTS: The adjusted risk of sudden unexpected death for citalopram did not differ significantly from that for the other SSRIs. The respective hazard ratios (HRs) for citalopram versus escitalopram, fluoxetine, paroxetine, and sertraline were 0.84 (95% CI, 0.40-1.75), 1.24 (95% CI, 0.75-2.05), 0.75 (95% CI, 0.45-1.24), and 1.53 (95% CI, 0.91-2.55). There were no significant differences for sudden cardiac death or all study deaths, nor were there significant differences among high-risk patients (≥ 60 years of age, upper quartile baseline cardiovascular risk). Escitalopram users had no significantly increased risk for any study end point. CONCLUSIONS: We found no evidence that risk of sudden unexpected death, sudden cardiac death, or total mortality for high-dose citalopram and escitalopram differed significantly from that for comparable doses of fluoxetine, paroxetine, and sertraline.

Depression requiring anti-depressant drug therapy in adult congenital heart disease: prevalence, risk factors, and prognostic value.

BACKGROUND: Depression is prevalent in adults with congenital heart disease (ACHD), but limited data on the frequency of anti-depressant drug (ADD) therapy and its impact on outcome are available. METHODS AND RESULTS: We identified all ACHD patients treated with ADDs between 2000 and 2011 at our centre. Of 6162 patients under follow-up, 204 (3.3%) patients were on ADD therapy. The majority of patients were treated with selective serotonin-reuptake inhibitors (67.4%), while only 17.0% of patients received tricyclic anti-depressants. Twice as many female patients used ADDs compared with males (4.4 vs. 2.2%, P < 0.0001). The percentage of patients on ADDs increased with disease complexity (P < 0.0001) and patient age (P < 0.0001). Over a median follow-up of 11.1 years, 507 (8.2%) patients died. After propensity score matching, ADD use was found to be significantly associated with worse outcome in male ACHD patients [hazard ratio 1.44 (95% confidence interval 1.17-1.84)]. There was no evidence that this excess mortality was directly related to ADD therapy, QT-prolongation, or malignant arrhythmias. However, males taking ADDs were also more likely to miss scheduled follow-up appointments compared with untreated counterparts, while no such difference in clinic attendance was seen in females. CONCLUSIONS: The use of ADD therapy in ACHD relates to gender, age, and disease complexity. Although, twice as many female patients were on ADDs, it were their male counterparts, who were at increased mortality risk on therapy. Furthermore, males on ADDs had worse adherence to scheduled appointments suggesting the need for special medical attention and possibly psychosocial intervention for this group of patients.

Use of genetic testing to identify sudden cardiac death syndromes.

Sudden cardiac death (SCD) is a leading cause of mortality worldwide. Although coronary artery disease remains the most common substrate for SCD, primary cardiac genetic diseases, presenting with or without structural heart abnormalities, play a significant role. In the last 30 years, the study of large family pedigrees allowed the discovery of causative genes unveiling the genetic basis of diseases such as primary cardiomyopathies and arrhythmia syndromes, which are known to increase the risk of SCD. However, recent technological advancement with the ability to perform massive parallel sequencing and analyze the entire genome has uncovered a higher level of complexity in the genetic predisposition for cardiac diseases, which are usually characterized by Mendelian inheritance patterns. Clinical genetic testing, historically shaped around a monogenic Mendelian disorder paradigm, is now facing the challenge to adopt and adapt to a more complex model in which a significant portion of subjects may present with multi-allelic inheritance involving additional genes that could modulate the severity and type of disease-related phenotypes. Here, we will try to provide a viewpoint that will hopefully foster further debate in the field.

Long QT molecular autopsy in sudden infant death syndrome.

OBJECTIVE: To describe experience of long QT (LQT) molecular autopsy in sudden infant death syndrome (SIDS). DESIGN: Descriptive audit from two distinct periods: (1) A prospective, population-based series between 2006 and 2008 ('unselected'). (2) Before and after 2006-2008, with testing guided by a cardiac genetic service ('selected'). LQT genes 1, 2, 3, 5, 6 and 7 were sequenced. Next of kin were offered cardiac evaluation. SETTING: New Zealand. PATIENTS: 102 SIDS cases. INTERVENTIONS: Nil. Main outcome measures Detection of genetic variants. RESULTS: Maori 49 (47%), and Pacific island 24 (23%), infants were over-represented. Risk factors were common; bed sharing was reported in 49%. Rare genetic variants were commoner within the selected than unselected populations (5 of 31 infants (16%) vs 3 of 71 infants (4%) p < 0.05). In the selected population two infants had variants of definite or probable pathogenicity (KCNQ1, E146K; KCNH2, R1047L), two had novel variants of possible pathogenicity in SCN5A (I795F, F1522Y) and one had R1193Q in SCN5A, of doubtful pathogenicity. R1193Q was also the only variant in the three cases from the unselected population and occurred as a second variant with R1047L. Engaging families proved challenging. Only 3 of 8 (38%) variant-positive cases and 18 of 94 (19%) of variant-negative families participated in cardiac/genetic screening. CONCLUSIONS: LQT molecular autopsy has a very low diagnostic yield among unselected SIDS cases where risk factors are common. Diagnostic yield can be higher with case selection. Engagement of the family prior to genetic testing is essential to counsel for the possible uncertainty of the results and to permit family genotype-phenotype cosegregation studies.

Genetic characteristics of children and adolescents with long-QT syndrome diagnosed by school-based electrocardiographic screening programs.

BACKGROUND: A school-based electrocardiographic screening program has been developed in Japan. However, few data are available on the genetic characteristics of pediatric patients with long-QT syndrome who were diagnosed by this program. METHODS AND RESULTS: A total of 117 unrelated probands aged ≤18 years were the subjects who were referred to our centers for genetic testing. Of these, 69 subjects diagnosed by the program formed the screened group. A total of 48 subjects were included in the clinical group and were diagnosed with long-QT syndrome-related symptoms, familial study, or by chance. Mutations were classified as radical, of high probability of pathogenicity, or of uncertain significance. Two subjects in the clinical group died. Genotypes were identified in 50 (72%) and 23 (48%) of subjects in the screened and clinical groups, respectively. Of the KCNQ1 or KCNH2 mutations, 31 of 33 (94%) in the screened group and 15 of 16 (94%) in the clinical group were radical and of high probability of pathogenicity. Prevalence of symptoms before (9/69 versus 31/48; P<0.0001) and after (12/69 versus 17/48; P=0.03) diagnosis was significantly lower in the screened group when compared with that in the clinical group although the QTc values, family history of long-QT syndrome, sudden death, and follow-up periods were not different between the groups. CONCLUSIONS: These data suggest that the screening program may be effective for early diagnosis of long-QT syndrome that may allow intervention before symptoms. In addition, screened patients should have follow-up equivalent to clinically identified patients.

Molecular analysis of potassium ion channel genes in sudden death cases among patients administered psychotropic drug therapy: are polymorphisms in LQT genes a potential risk factor?

Psychotropic drugs can pose the risk of acquired long QT syndrome (LQTS). Unexpected autopsy-negative sudden death in patients taking psychotropic drugs may be associated with prolonged QT intervals and life-threatening arrhythmias. We analyzed genes that encode for cardiac ion channels and potentially associated with LQTS, examining specifically the potassium channel genes KCNQ1 and KCNH2 in 10 cases of sudden death involving patients administered psychotropic medication in which autopsy findings identified no clear cause of death. We amplified and sequenced all exons of KCNQ1 and KCNH2, identifying G643S, missense polymorphism in KCNQ1, in 6 of the 10 cases. A study analysis indicated that only 11% of 381 healthy Japanese individuals carry this polymorphism. Reports of previous functional analyses indicate that the G643S polymorphism in the KCNQ1 potassium channel protein causes mild I(Ks) channel dysfunction. Our present study suggests that administering psychotropic drug therapy to individuals carrying the G643S polymorphism may heighten the risk of prolonged QT intervals and life-threatening arrhythmias. Thus, screening for the G643S polymorphism before prescribing psychotropic drugs may help reduce the risk of unexpected sudden death.

Left thoracoscopic sympathectomy for cardiac denervation in patients with life-threatening ventricular arrhythmias.

BACKGROUND: We reported the outcomes of a single-institution experience using video-assisted thoracoscopic left cardiac sympathetic denervation as an adjunctive therapeutic technique in pediatric and young adult patients with life-threatening ventricular arrhythmias. METHODS: We conducted a retrospective clinical review of all patients who underwent left cardiac sympathetic denervation by means of video-assisted thoracoscopic surgery at our institution. From August 2000 to December 2011, 24 patients (13 with long QT syndrome, 9 with catecholaminergic polymorphic ventricular tachycardia, and 2 with idiopathic ventricular tachycardia) were identified from the cardiology database and surgical records. RESULTS: There were no intraoperative complications. The median postoperative length of stay was 2 days (range, 1-32 days). There were no major perioperative complications. Longer-term follow-up was available in 22 of 24 patients at a median follow-up of 28 months (range, 4-131 months). Sixteen (73%) of the 22 patients experienced a marked reduction in their arrhythmia burden, with 12 (55%) becoming completely arrhythmia free after sympathectomy. Six (27%) of the patients were nonresponsive to treatment; each had persistent symptoms at follow-up. CONCLUSIONS: Video-assisted thoracoscopic left cardiac sympathetic denervation can be safely and effectively performed in most patients with life-threatening ventricular arrhythmias. This minimally invasive procedure is a promising adjunctive therapeutic option that achieves a beneficial response in most symptomatic patients. These results support the inclusion of thoracoscopic cardiac sympathetic denervation among the treatment armamentarium in all patients with ventricular arrhythmias refractive to conventional medical therapy.

Long QT interval in Turner syndrome--a high prevalence of LQTS gene mutations.

OBJECTIVES: QT-interval prolongation of unknown aetiology is common in Turner syndrome. This study set out to explore the presence of known long QT mutations in Turner syndrome and to examine the corrected QT-interval (QTc) over time and relate the findings to the Turner syndrome phenotype. METHODS: Adult women with Turner syndrome (n = 88) were examined thrice and 68 age-matched healthy controls were examined once. QTc was measured by one blinded reader (intra-reader variability: 0.7%), and adjusted for influence of heart rate by Bazett's (bQTc) and Hodges's formula (hQTc). The prevalence of mutations in genes related to Long QT syndrome was determined in women with Turner syndrome and a QTc >432.0 milliseconds (ms). Echocardiographic assessment of aortic valve morphology, 24-hour blood pressures and blood samples were done. RESULTS: The mean hQTc in women with Turner syndrome (414.0 ± 25.5 ms) compared to controls (390.4 ± 17.8 ms) was prolonged (p<0.001) and did not change over time (416.9 ± 22.6 vs. 415.6 ± 25.5 ms; p =0.4). 45,X karyotype was associated with increased hQTc prolongation compared to other Turner syndrome karyotypes (418.2 ± 24.8 vs. 407.6 ± 25.5 ms; p = 0.055). In women with Turner syndrome and a bQTc >432 ms, 7 had mutations in major Long QT syndrome genes (SCN5A and KCNH2) and one in a minor Long QT syndrome gene (KCNE2). CONCLUSION: There is a high prevalence of mutations in the major LQTS genes in women with TS and prolonged QTc. It remains to be settled, whether these findings are related to the unexplained excess mortality in Turner women. CLINICAL TRIAL REGISTRATION: NCT00624949. https://register.clinicaltrials.gov/prs/app/action/SelectProtocol/sid/S0001FLI/selectaction/View/ts/3/uid/U000099E.