Mothers with long QT syndrome are at increased risk for fetal death: findings from a multicenter international study

Further exploration of cardiac channelopathy and cardiomyopathy genes in stillbirth

OBJECTIVE

To explore genetic variation including whole genome copy number variation and sequence analysis of 98 genes associated with pediatric or adult cardiomyopathies, cardiac channelopathies, and sudden death in an unexplained intrauterine fetal death cohort.

METHODS

The study population included 55 stillbirth cases that remained unexplained after thorough postmortem examination, excluding maternal, fetal, and placental causes of stillbirth. Molecular karyotyping was performed in 55 cases and the trio exome sequencing approach was applied in 19 cases.

RESULTS

The analysis revealed six rare variants with predicted effects on protein function in six genes (CASQ2, DSC2, KCNE1, LDB3, MYH6, and SCN5A) previously reported in cases of stillbirth or severe early onset pediatric cardiac related phenotypes. When applying strict American College of Genetics and Genomics classification guidelines, these are still variants of uncertain significance.

CONCLUSIONS

Several potentially stillbirth-related genetic variants were detected in our cohort, adding to the growing literature on cardiac phenotype gene variation in stillbirth. However, the mechanisms of action, gene-gene interaction, and contribution of the uterine environment are still to be deciphered. In order to advance our knowledge of the genetics of unexplained fetal death, there is an evident need for international collaboration and field standardization.

Assessment of Severity of Long QT Syndrome Phenotype and Risk of Fetal Death

BACKGROUND

It has been postulated that long QT syndrome (LQTS) can cause fetal loss through putative adverse effects of the channelopathy on placenta and myometrial function. The authors aimed to describe the fetal death rate in a population of pregnant women with long QT syndrome and investigate whether women with more severe phenotype had worse fetal outcomes.

METHODS AND RESULTS

The authors retrospectively evaluated fetal outcomes of 64 pregnancies from 23 women with long QT syndrome followed during pregnancy in a tertiary pregnancy and heart disease program. Thirteen of 64 pregnancies (20%) resulted in a fetal loss, 12 miscarriages (19%), and 1 stillbirth (1.6%). Baseline maternal characteristics, including age and use of β-blockers, did not differ between women who experienced a fetal death or not. Maternal corrected QT interval (QTc) was significantly longer in pregnancies that resulted in fetal death compared with live births (median, 518 ms [interquartile range (IQR), 482-519 ms] versus 479 ms [IQR, 454-496 ms], P<0.001). Mothers treated with β-blockers had babies born at term with lower birth weight compared with untreated women (2973±298 g versus 3470±338 g, P=0.002). In addition, the birth weight of babies born at term to treated women with QTc >500 ms was significantly lower compared with women with QTc <500 ms (2783±283 g versus 3084±256 g, P=0.029).

CONCLUSIONS

Women with long QT syndrome with more severe phenotypes have a higher incidence of fetal death. Maternal QTc is longer in pregnancies that result in fetal loss, and the birth weight of babies born to patients taking β-blockers with a QTc >500 ms is lower, suggesting that patients with more marked phenotype may experience worse fetal outcomes.

Effects of cohort, genotype, variant, and maternal β-blocker treatment on foetal heart rate predictors of inherited long QT syndrome

AIMS

In long QT syndrome (LQTS), primary prevention improves outcome; thus, early identification is key. The most common LQTS phenotype is a foetal heart rate (FHR) < 3rd percentile for gestational age (GA) but the effects of cohort, genotype, variant, and maternal β-blocker therapy on FHR are unknown. We assessed the influence of these factors on FHR in pregnancies with familial LQTS and developed a FHR/GA threshold for LQTS.

METHODS AND RESULTS

In an international cohort of pregnancies in which one parent had LQTS, LQTS genotype, familial variant, and maternal β-blocker effects on FHR were assessed. We developed a testing algorithm for LQTS using FHR and GA as continuous predictors. Data included 1966 FHRs at 7-42 weeks' GA from 267 pregnancies/164 LQTS families [220 LQTS type 1 (LQT1), 35 LQTS type 2 (LQT2), and 12 LQTS type 3 (LQT3)]. The FHRs were significantly lower in LQT1 and LQT2 but not LQT3 or LQTS negative. The LQT1 variants with non-nonsense and severe function loss (current density or β-adrenergic response) had lower FHR. Maternal β-blockers potentiated bradycardia in LQT1 and LQT2 but did not affect FHR in LQTS negative. A FHR/GA threshold predicted LQT1 and LQT2 with 74.9% accuracy, 71% sensitivity, and 81% specificity.

CONCLUSION

Genotype, LQT1 variant, and maternal β-blocker therapy affect FHR. A predictive threshold of FHR/GA significantly improves the accuracy, sensitivity, and specificity for LQT1 and LQT2, above the infant's a priori 50% probability. We speculate this model may be useful in screening for LQTS in perinatal subjects without a known LQTS family history.

2023 HRS expert consensus statement on the management of arrhythmias during pregnancy

This international multidisciplinary expert consensus statement is intended to provide comprehensive guidance that can be referenced at the point of care to cardiac electrophysiologists, cardiologists, and other health care professionals, on the management of cardiac arrhythmias in pregnant patients and in fetuses. This document covers general concepts related to arrhythmias, including both brady- and tachyarrhythmias, in both the patient and the fetus during pregnancy. Recommendations are provided for optimal approaches to diagnosis and evaluation of arrhythmias; selection of invasive and noninvasive options for treatment of arrhythmias; and disease- and patient-specific considerations when risk stratifying, diagnosing, and treating arrhythmias in pregnant patients and fetuses. Gaps in knowledge and new directions for future research are also identified.

The genetic approach to stillbirth: A »systematic review«

Unexplained stillbirth is defined as a stillbirth with no known cause after the exclusion of common causes, including obstetric complications, infections, placental insufficiency or abruption, umbilical cord complications, and congenital abnormalities with or without known genetic cause. More than 60% of stillbirth cases remain unexplained. The aim of this systematic review was to investigate the known genetic causes of unexplained stillbirth cases and to evaluate the current position and future directions for the use of genetic and genomic testing in expanding the knowledge in this field. A systematic search through several databases was performed using the keywords genetics and stillbirths in humans. Different methods to detect various types of causal genetic aberrations have been used in the past decades, from standard karyotyping to novel methods such as chromosomal microarray analysis and next generation sequencing technologies. Apart from common chromosomal aneuploidies, a promising hypothesis about genetic causes included genes related to cardiomyopathies and channelopathies. However, these were tested in the research settings, since molecular karyotyping is currently the standard approach in the routine evaluation of genetic causes of stillbirth. Hereby, we provide evidence that expanding knowledge using novel genetic and genomic testing might uncover new genetic causes of unexplained stillbirth.

A Small Scale Optically Pumped Fetal Magnetocardiography System

INTRODUCTION

Fetal magnetocardiography (fMCG) is considered the best technique for diagnosis of fetal arrhythmia. It is superior to more widely used methods such as fetal, fetal electrocardiography, and cardiotocography for evaluation of fetal rhythm. The combination of fMCG and fetal echocardiography can provide a more comprehensive evaluation of fetal cardiac rhythm and function than is currently possible. In this study, we demonstrate a practical fMCG system based on optically pumped magnetometers (OPMs).

METHODS

Seven pregnant women with uncomplicated pregnancies underwent fMCG at 26-36 weeks' gestation. The recordings were made using an OPM-based fMCG system and a person-sized magnetic shield. The shield is much smaller than a shielded room and provides easy access with a large opening that allows the pregnant woman to lie comfortably in a prone position.

RESULTS

The data show no significant loss of quality compared to data acquired in a shielded room. Measurements of standard cardiac time intervals yielded the following results: PR = 104 ± 6 ms, QRS = 52.6 ± 1.5 ms, and QTc = 387 ± 19 ms. These results are compatible with those from prior studies performed using superconducting quantum interference device (SQUID) fMCG systems.

CONCLUSIONS

To our knowledge, this is the first European fMCG device with OPM technology commissioned for basic research in a pediatric cardiology unit. We demonstrated a patient-friendly, comfortable, and open fMCG system. The data yielded consistent cardiac intervals, measured from time-averaged waveforms, compatible with published SQUID and OPM data. This is an important step toward making the method widely accessible.

Preventing and Treating Torsades de Pointes in the Mother, Fetus and Newborn in the Highest Risk Pregnancies with Inherited Arrhythmia Syndromes

The number of women of childbearing age who have been diagnosed in childhood with ion channelopathy and effectively treated using beta blockers, cardiac sympathectomy, and life-saving cardiac pacemakers/defibrillators is increasing. Since many of these diseases are inherited as autosomal dominant, offspring have about a 50% risk of having the disease, though many will be only mildly impacted during fetal life. However, highly complex delivery room preparation is increasingly needed in pregnancies with inherited arrhythmia syndromes (IASs). However, specific Doppler techniques show meanwhile a better understanding of fetal electrophysiology. The advent of fetal magnetocardiography (FMCG) now allows the detection of fetal Torsades de Pointes (TdP) ventricular tachycardia and other LQT-associated arrhythmias (QTc prolongation, functional second AV block, T-wave alternans, sinus bradycardia, late-coupled ventricular ectopy and monomorphic VT) in susceptible fetuses during the second and third trimester. These types of arrhythmias can be due to either de novo or familial Long QT Syndrome (LQTS), Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), or other IAS. It is imperative that the multiple specialists involved in the antenatal, peripartum, and neonatal care of these women and their fetuses/infants have the optimal knowledge, training and equipment in order to care for these highly specialized pregnancies and deliveries. In this review, we outline the steps to recognize symptomatic LQTS in either the mother, fetus or both, along with suggestions for evaluation and management of the pregnancy, delivery, or post-partum period impacted by LQTS.

A bibliometric review of 35 years of studies about preeclampsia

The purpose of this study is to investigate preeclampsia. It used the visualization tools of CiteSpace, VOSviewer, Gunnmap, Bibliometrix®, and Carrot2 to analyze 3,754 preeclampsia studies from 1985 to 2020 in Obstetrics and Gynecology areas. Carrot2 was used to explain each cluster in extra detail. The results found that there is an increasing trend in many publications related to preeclampsia from 1985 to 2020. The number of studies on preeclampsia has increased significantly in the last century. Analysis of the keywords found a strong relationship with preeclampsia concepts and keywords classified into five categories. Co-citation analysis was also performed which was classified into six categories. Reading the article offers important to support not only to grind the context of preeclampsia challenges but also to design a new trend in this field. The number of studies on preeclampsia has substantially improved over the decades ago. The findings of documents published from 1985 to 2020 showed three stages in research on this subject: 1985 to 1997 (a seeding stage), 1997-2005 (rapid growth stage), and 2005 onwards (development stage).

Genomic autopsy to identify underlying causes of pregnancy loss and perinatal death

Pregnancy loss and perinatal death are devastating events for families. We assessed 'genomic autopsy' as an adjunct to standard autopsy for 200 families who had experienced fetal or newborn death, providing a definitive or candidate genetic diagnosis in 105 families. Our cohort provides evidence of severe atypical in utero presentations of known genetic disorders and identifies novel phenotypes and disease genes. Inheritance of 42% of definitive diagnoses were either autosomal recessive (30.8%), X-linked recessive (3.8%) or autosomal dominant (excluding de novos, 7.7%), with risk of recurrence in future pregnancies. We report that at least ten families (5%) used their diagnosis for preimplantation (5) or prenatal diagnosis (5) of 12 pregnancies. We emphasize the clinical importance of genomic investigations of pregnancy loss and perinatal death, with short turnaround times for diagnostic reporting and followed by systematic research follow-up investigations. This approach has the potential to enable accurate counseling for future pregnancies.

Systematic review of long QT syndrome identified during fetal life

Fetal long QT syndrome (LQTS) may present with sinus bradycardia, functional 2:1 atrioventricular block (AVB), and ventricular arrhythmias (ventricular tachycardia [VT]/torsades de pointes [TdP]) and lead to fetal or postnatal death. We performed a systematic review and individual participant data meta-analysis of 83 studies reporting outcomes of 265 fetuses for which suspected LQTS was confirmed postnatally and determined risk of adverse perinatal and postnatal outcomes using logistic and stepwise logistic regression. A longer fetal QTc was more predictive of death than any other antenatal factor (receiver operating characteristic [ROC] area under the curve [AUC] 0.85; 95% confidence interval [CI] 0.66-1.00). Risk of death was significantly increased with fetal QTc >600 ms. Neither fetal heart rate nor heart rate z-score predicted death (ROC AUC 0.51; 95% CI 0.31-0.71; and ROC AUC 0.59; 95% CI 0.37-0.80, respectively). The combination of antenatal VT/TdP or functional 2:1 AVB and lack of family history of LQTS was also highly predictive of death (ROC AUC 0.82; 95% CI 0.76-0.88). Our data provide clinical screening tools to enable prediction and intervention for fetuses with LQTS at risk of death.

Fetal Arrhythmia Diagnosis and Pharmacologic Management

One of the most successful achievements of fetal intervention is the pharmacologic management of fetal arrhythmias. This management usually takes place during the second or third trimester. While most arrhythmias in the fetus are benign, both tachy‐ and bradyarrhythmias can lead to fetal hydrops or cardiac dysfunction and require treatment under certain conditions. This review will highlight precise diagnosis by fetal echocardiography and magnetocardiography, the 2 primary means of diagnosing fetuses with arrhythmia. Additionally, transient or hidden arrhythmias such as bundle branch block, QT prolongation, and torsades de pointes, which can lead to cardiomyopathy and sudden unexplained death in the fetus, may also need pharmacologic treatment. The review will address the types of drug therapies; current knowledge of drug usage, efficacy, and precautions; and the transition to neonatal treatments when indicated. Finally, we will highlight new assessments, including the role of the nurse in the care of fetal arrhythmias. The prognosis for the human fetus with arrhythmias continues to improve as we expand our ability to provide intensive care unit–like monitoring, to better understand drug treatments, to optimize subsequent pregnancy monitoring, to effectively predict timing for delivery, and to follow up these conditions into the neonatal period and into childhood. Coordinated initiatives that facilitate clinical fetal research are needed to address gaps in knowledge and to facilitate fetal drug and device development.

Contribution of Fetal Magnetocardiography to Diagnosis, Risk Assessment, and Treatment of Fetal Arrhythmia

Background

Fetal echocardiography has been the mainstay of fetal arrhythmia diagnosis; however, fetal magnetocardiography (fMCG) has recently become clinically available. We sought to determine to what extent fMCG contributed to the precision and accuracy of fetal arrhythmia diagnosis and risk assessment, and in turn, how this altered pregnancy management.

Methods and Results

We reviewed fMCG tracings and medical records of 215 pregnancies referred to the Biomagnetism Laboratory, UW‐Madison, over the last 10 years, because of fetal arrhythmia or risk of arrhythmia. We compared referral diagnosis and treatment with fMCG diagnosis using a rating scale and restricted our review to the 144 subjects from the tachycardia, bradycardia/AV block, and familial long QT syndrome categories. Additional fMCG findings beyond those of the referring echocardiogram, or an alternative diagnosis were seen in 117/144 (81%), and 81 (56%) were critical changes. Eight (5.5%) had resolution of arrhythmia before fMCG. At least moderate changes in management were seen in 109/144 (76%) fetuses, of which 35/144 (24%) were major. The most diverse fMCG presentation was long QT syndrome, present in all 3 referral categories. Four of 5 stillbirths were seen with long QT syndrome. Nine fetuses showed torsades de pointes ventricular tachycardia, of which only 2 were recognized before fMCG.

Conclusions

FMCG has a significant impact on prenatal diagnosis and management of arrhythmias or familial arrhythmia risk, which cannot be fully met by existing technology. The combination of fMCG and fetal echocardiography in fetal care centers will be needed in the future to optimize care.

Contemporary Maternal and Fetal Outcomes in Treatment of LQTS during Pregnancy: Is Nadolol Bad for the Fetus?

BACKGROUND

Beta blocker therapy, specifically nadolol, is the recommended treatment for long QT syndrome (LQTS). Previous studies assessing maternal and fetal outcomes were published prior to nadolol era.

OBJECTIVES

The purpose of this study was to examine contemporary maternal and fetal outcomes in treatment of LQTS during pregnancy.

METHODS

We queried the Inherited Arrhythmia Database at Cleveland Clinic and identified all pregnant LQTS patients from January 2001 to January 2020. Collected data included use and timing of beta-blockers, maternal arrhythmia events, fetal growth restriction, neonatal hypoglycemia and bradycardia.

RESULTS

Among 68 live-birth pregnancies in 31 women with LQTS (mean age 29 ± 5.9 years, mean QTc 468 ± 39 ms), there were 5 arrhythmia events in 4 mothers. All arrhythmia events occurred in the post-partum period and there were no arrhythmia events in patients taking beta blockers. In diagnosed LQTS patients treated with beta blockers (n=27, 41%), nadolol was the most commonly prescribed agent throughout pregnancy and postpartum period (n=16, 60%). The rate of intrauterine growth restriction (IUGR) was not significantly different in fetuses exposed to beta blockers vs. unexposed (p=0.08). In the postnatal period, hypoglycemia was not seen and one patient in the exposure group had bradycardia.

CONCLUSIONS

Arrhythmia events were only seen in the post-partum period in those not treated with beta blockers. Events occurred as late as 9 months postpartum. Beta blocker therapy, specifically nadolol, was not associated with higher incidence of IUGR. Moreover, neonatal bradycardia was rare and hypoglycemia was not observed.

Pitfalls of International Classification of Diseases - Perinatal mortality in analysing stillbirths

OBJECTIVES

This study aimed to evaluate the trend of stillbirth from 2009 to 2018. The causes of stillbirth were classified using the International Classification of Diseases - Perinatal Mortality (ICD-PM).

STUDY DESIGN AND METHODS

A retrospective chart review was performed on 135 stillbirths from 2009 to 2018 in a tertiary university teaching hospital. The annual stillbirth rate was calculated, and the trend was evaluated. The cause of death was reclassified using ICD-PM.

RESULTS

The stillbirth rate was 3.70 per 1000 total births, and it remained stable over the studied period (P = 0.238). Most of the stillbirth (97.8%) were antepartum deaths. The proportion of unexplained stillbirth was reduced from 57% to 18.5% after reclassified by ICD-PM coding. Another major cause of antepartum stillbirths was disorders related to fetal growth, which consisted of mothers with medical and surgical conditions (11%, n = 15, ICD-PM code A5, M4) or mothers with complications of placenta, cord and membranes (8.9%, n = 12, ICD-PM code A5, M1).

CONCLUSION

The use of ICD-PM was useful in reducing the proportion of unexplained stillbirths. ICD-PM has the advantages of coding related to the timing of stillbirth and associated maternal conditions. Pitfalls including the unclear use of the code A3-'antepartum hypoxia,' guidance on coding of well-controlled maternal medical conditions and placental pathology and the importance of subcategorisation need to be addressed.

Recurrent Pregnancy Loss and Concealed Long-QT Syndrome

Background

Recurrent pregnancy loss affects 1% to 2% of couples attempting childbirth. A large fraction of all cases remains idiopathic, which warrants research into monogenic causes of this distressing disorder.

Methods and Results

We investigated a nonconsanguineous Estonian family who had experienced 5 live births, intersected by 3 early pregnancy losses, and 6 fetal deaths, 3 of which occurred during the second trimester. No fetal malformations were described at the autopsies performed in 3 of 6 cases of fetal death. Parental and fetal chromosomal abnormalities (including submicroscopic) and maternal risk factors were excluded. Material for genetic testing was available from 4 miscarried cases (gestational weeks 11, 14, 17, and 18). Exome sequencing in 3 pregnancy losses and the mother identified no rare variants explicitly shared by the miscarried conceptuses. However, the mother and 2 pregnancy losses carried a heterozygous nonsynonymous variant, resulting in p.Val173Asp (rs199472695) in the ion channel gene KCNQ1. It is expressed not only in heart, where mutations cause type 1 long‐QT syndrome, but also in other tissues, including uterus. The p.Val173Asp variant has been previously identified in a patient with type 1 long‐QT syndrome, but not reported in the Genome Aggregation Database. With heterologous expression in CHO cells, our in vitro electrophysiologic studies indicated that the mutant slowly activating voltage‐gated K+ channel (I_Ks) is dysfunctional. It showed reduced total activating and deactivating currents (P<0.01), with dramatically positive shift of voltage dependence of activation by ≈10 mV (P<0.05).

Conclusions

The current study uncovered concealed maternal type 1 long‐QT syndrome as a potential novel cause behind recurrent fetal loss.

Sex Disparities in Sudden Cardiac Death

The overall incidence of sudden cardiac death is considerably lower among women than men, reflecting significant and often under-recognized sex differences. Women are older at time of sudden cardiac death, less likely to have a prior cardiac diagnosis, and less likely to have coronary artery disease identified on postmortem examination. They are more likely to experience their death at home, during sleep, and less likely witnessed. Women are also more likely to present in pulseless electrical activity or systole rather than ventricular fibrillation or ventricular tachycardia. Conversely, women are less likely to receive bystander cardiopulmonary resuscitation or receive cardiac intervention post-arrest. Underpinning sex disparities in sudden cardiac death is a paucity of women recruited to clinical trials, coupled with an overall lack of prespecified sex-disaggregated evidence. Thus, predominantly male-derived data form the basis of clinical guidelines. This review outlines the critical sex differences concerning epidemiology, cause, risk factors, prevention, and outcomes. We propose 4 broad areas of importance to consider: physiological, personal, community, and professional factors.

Management of Congenital Long-QT Syndrome: Commentary From the Experts

While published guidelines are useful in the care of patients with long-QT syndrome, it can be difficult to decide how to apply the guidelines to individual patients, particularly those with intermediate risk. We explored the diversity of opinion among 24 clinicians with expertise in long-QT syndrome. Experts from various regions and institutions were presented with 4 challenging clinical scenarios and asked to provide commentary emphasizing why they would make their treatment recommendations. All 24 authors were asked to vote on case-specific questions so as to demonstrate the degree of consensus or divergence of opinion. Of 24 authors, 23 voted and 1 abstained. Details of voting results with commentary are presented. There was consensus on several key points, particularly on the importance of the diagnostic evaluation and of β-blocker use. There was diversity of opinion about the appropriate use of other therapeutic measures in intermediate-risk individuals. Significant gaps in knowledge were identified.

Management of Long QT Syndrome in Women Before, During, and After Pregnancy

Congenital long QT syndrome (LQTS) is a primary genetic and electrical disorder that increases risk for torsades de pointes, syncope, and sudden death. Post-pubertal women with LQTS require specialized multidisciplinary management before, during, and after pregnancy involving cardiology and obstetrics to reduce risk for cardiac events in themselves and their fetuses and babies. The risk of potentially life-threatening events is lower during pregnancy but increases significantly during the 9-month postpartum period. Treatment of women with LQTS with a preferred β-blocker at optimal doses along with close monitoring are indicated throughout pregnancy and during the high-risk postpartum period.

A Validation Study on the Frequency and Natural History of Miscarriages Using the Spanish Primary Care Database BIFAP

(1) Background: There is a major gap of knowledge towards the natural history of miscarriages in electronic medical records. We aimed to calculate the frequency of miscarriages using data from BIFAP database. (2) Methods: We identified all pregnancy losses and carried out a multistep validation exercise. Potential cases with positive predictive values (PPV) of miscarriage confirmation <85% or those confirming other pregnancy loss were excluded. Kaplan–Meier figures and incidence rates (IRs) of miscarriage with 95% confidence intervals (CIs) expressed by 1000 person-weeks were calculated. Stratifying analysis by age, specific high-risk groups, and drug exposure within the pre-pregnancy period were performed restricted to women with recording last menstrual period (LMP). (3) Results: Women with confirmed miscarriage (N = 18,070), tended to be older, with higher frequency of comorbidities and drug utilization. Restricting to women with LPM recorded, IR of miscarriage was 10.89 (CI 95% 10.68–11.10) per 1000 women-weeks, with a median follow-up of 10 weeks (IQR: 8–12). The IR according to age was: 2.71 (CI 95% 2.59–2.84) in those aged <30 years compared to 9.11 (CI 95% 8.55–9.70) in women aged ≥40 years. Advanced maternal age (Hazard Ratio (HR, 95% confidence interval) CI 95%: 3.34 (3.08–3.62)), use of antihypertensives (1.49 (1.21–1.84), and use of drugs classified as D or X during pregnancy (1.17 (1.07–1.29)) showed to be positive predictors associated with increased risk of miscarriages. (4) Conclusion: BIFAP database can be used to identify women suffering from miscarriages, which will serve to further study risk factors associated with miscarriages with special attention to drug utilization.

Arrhythmic risk during pregnancy and postpartum in patients with long QT syndrome

Congenital long QT syndrome (LQTS) is a genetic disorder characterized by a prolonged QT interval in the surface electrocardiogram (ECG) that predisposes affected individuals to arrhythmic syncope, ventricular torsades-de-pointes, and sudden cardiac death at a young age. Investigations of large patient cohorts revealed sex-related differences in the LQTS phenotype. Adult women with LQTS are at higher risk for cardiac arrhythmias than are adult men with LQTS. Sex hormones are thought to play the primary role for these gender differences. Clinical experience and translational studies indicated that females with LQTS have a lower risk for cardiac arrhythmias during pregnancy and elevated risk in the postpartum period due to contrasting effects of estradiol and progesterone, as well as postpartum hormones on the action potential and arrhythmia substrate. However, this pro- or anti-arrhythmic potential of hormones varies depending on the underlying genotype, partly since sex hormones have distinct effects on different (affected) cardiac ion channels. Thus, a comprehensive evaluation of women with LQTS prior to and during pregnancy, during labor, and in the postpartum period with consideration of the patient’s disease- and gene-specific risk factors is essential to providing precision management in this patient group. This review discusses the current understanding of hormonal influences in LQTS and provides practical guidance for the optimal management of LQTS patients during pregnancy, delivery, and the postpartum period.

Sex-Related Differences in Cardiac Channelopathies: Implications for Clinical Practice

Sex-related differences in prevalence, clinical presentation, and outcome of cardiac channelopathies are increasingly recognized, despite their autosomal transmission and hence equal genetic predisposition among sexes. In congenital long-QT syndrome, adult women carry a greater risk for Torsades de pointes and sudden cardiac death than do men. In contrast, Brugada syndrome is observed predominantly in adult men, with a considerably higher risk of arrhythmic sudden cardiac death in adult men than in women. In both conditions, the risk for arrhythmias varies with age. Sex-associated differences appear less evident in other cardiac channelopathies, likely a reflection of their rare(r) occurrence and our limited knowledge. In several cardiac channelopathies, sex-specific predictors of outcome have been identified. Together with genetic and environmental factors, sex hormones contribute to the sex-related disparities in cardiac channelopathies through modulation of the expression and function of cardiac ion channels. Despite these insights, essential knowledge gaps exist in the mechanistic understanding of these differences, warranting further investigation. Precise application of the available knowledge may improve the individualized care of patients with cardiac channelopathies. Promoting the reporting of sex-related phenotype and outcome parameters in clinical and experimental studies and advancing research on cardiac channelopathy animal models should translate into improved patient outcomes. This review provides a critical digest of the current evidence for sex-related differences in cardiac channelopathies and emphasizes their clinical implications and remaining gaps requiring further research.

Intrauterine Growth Retardation in Pregnant Women with Long QT Syndrome Treated with Beta-Receptor Blockers

Pregnant women with inherited long QT syndrome (iLQTS) are at an increased risk for preterm delivery and intrauterine growth retardation (IUGR) due to their underlying disease. Additionally, they are at a risk of arrhythmogenic events, particularly during the postpartum period because of physiological changes and increased emotional/physical stress. β-receptor blockers can effectively prevent life-threatening Torsades de Pointes ventricular tachycardia and they are the treatment of choice in iLQTS. Use of β-receptor blockers in pregnancy is recommended, although IUGR is commonly reported for prenatally exposed infants. IUGR, particularly in preterm infants, can result in adverse neonatal outcomes. This review was performed to support clinicians in their selection of β-receptor blocker treatment for their pregnant iLQTS women by (i) summarizing the available literature addressing the impact of different β-receptor blockers on IUGR and (ii) reporting additional aspects which might influence the β-receptor blocker selection. In general, experts recommend to use nonselective β-receptor blockers, such as nadolol and propranolol, for iLQTS management as these drugs seem to be superior in effectiveness. However, β-1-selective receptor blockers, such as bisoprolol or metoprolol, seem to affect less likely uterine contraction, peripheral vasodilation, and are associated with lower IUGR rates and fetal hypoglycemia. They are therefore recommended, except atenolol, as first-line therapy for pregnant women. Additionally, maternal factors such as iLQTS genotype, other underlying comorbidities (e.g., diabetes mellitus type 1, asthma bronchiale), and uteroplacental dysfunction or fetal factors have to be taken into account. Therefore, each woman with iLQTS who wants to become pregnant should be well-advised for a personalized β-receptor blocker therapy according to the individual risk-benefit evaluation by a multidisciplinary team of cardiologists, gynecologists, pediatric cardiologists, neonatologists, and clinical pharmacologists. During pregnancy, a close monitoring of IUGR and, after birth, monitoring of bradycardia, hypoglycemia, and respiratory depression in the neonate is mandatory. This review summarizes available data on β-receptor blocker-related risk for IUGR in prenatally exposed infants and illustrates which factors might influence β-receptor blocker selection with the aim to support clinicians in their pharmacological management of their pregnant iLQTS patients.

KCNQ1 and Long QT Syndrome in 1/45 Amish: The Road From Identification to Implementation of Culturally Appropriate Precision Medicine

Supplemental Digital Content is available in the text.

In population-based research exome sequencing, the path from variant discovery to return of results is not well established. Variants discovered by research exome sequencing have the potential to improve population health.

Inherited cardiac arrhythmias

The main inherited cardiac arrhythmias are long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome. These rare diseases are often the underlying cause of sudden cardiac death in young individuals and result from mutations in several genes encoding ion channels or proteins involved in their regulation. The genetic defects lead to alterations in the ionic currents that determine the morphology and duration of the cardiac action potential, and individuals with these disorders often present with syncope or a life-threatening arrhythmic episode. The diagnosis is based on clinical presentation and history, the characteristics of the electrocardiographic recording at rest and during exercise and genetic analyses. Management relies on pharmacological therapy, mostly β-adrenergic receptor blockers (specifically, propranolol and nadolol) and sodium and transient outward current blockers (such as quinidine), or surgical interventions, including left cardiac sympathetic denervation and implantation of a cardioverter-defibrillator. All these arrhythmias are potentially life-threatening and have substantial negative effects on the quality of life of patients. Future research should focus on the identification of genes associated with the diseases and other risk factors, improved risk stratification and, in particular for Brugada syndrome, effective therapies.

Cardiac arrhythmias in pregnant women: need for mother and offspring protection

Cardiac arrhythmias are the most common cardiac complication reported in pregnant women with and without structural heart disease (SHD); they are more frequent among women with SHD, such as cardiomyopathy and congenital heart disease (CHD). While older studies had indicated supraventricular tachycardia as the most common tachyarrhythmia in pregnancy, more recent data indicate an increase in the frequency of arrhythmias, with atrial fibrillation (AF) emerging as the most frequent arrhythmia in pregnancy, attributed to an increase in maternal age, cardiovascular risk factors and CHD in pregnancy. Importantly, the presence of any tachyarrhythmia during pregnancy may be associated with adverse maternal and fetal outcomes, including death. Thus, both the mother and the offspring need to be protected from such consequences. The use of antiarrhythmic drugs (AADs) depends on clinical presentation and on the presence of underlying SHD, which requires caution as it promotes pro-arrhythmia. In hemodynamically compromised women, electrical cardioversion is successful and safe to both mother and fetus. Use of beta-blockers appears quite safe; however, caution is advised when using other AADs, while no AAD should be used, if at all possible, during the first trimester when organogenesis takes place. Regarding the anticoagulation regimen in patients with AF, warfarin should be substituted with heparin during the first trimester, while direct oral anticoagulants are not indicated given the lack of data in pregnancy. Finally, for refractory arrhythmias, ablation and/or device implantation can be performed with current techniques in pregnant women, when needed, using minimal exposure to radiation. All these issues and relevant current guidelines are herein reviewed.