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

Palpitations in puerperium-a self-recorded smart watch ECG gives the hint to hormone-induced ventricular arrhythmia: case report

Background

Gender-related aspects in cardiac arrhythmias have gained increasing attention, still the understanding of peripartum electrical disorders remains vague.

Case summary

A 28-year-old woman developed palpitations and presyncopes during the post-partum period after her second pregnancy. Palpitations remained unclear until a self-recorded single-lead smartwatch ECG revealed a complete episode of a fast broad complex tachycardia (260 b.p.m.) that led to hospital admission. Echocardiography, cardiac magnetic resonance imaging, and exercise testing, showed no relevant abnormalities. Recording the tachycardia in a 12-lead-ECG could eventually be achieved revealing an inferior axis and positive concordance in the precordial leads. Episodes of ventricular tachycardia (VT) could be provoked by breast feeding and mental stress, but not induced in two electrophysiological studies. Genetic testing was normal. The patient continued to experience repeated, self-terminating VT episodes, lasting between 10 and 40 s, leading to presyncopes and a syncope with a fall. The beginning of symptoms subsequent to child birth and frequent premature ventricular contractions in her first pregnancy made hormone-induced arrhythmia a tentative diagnosis. Heart rate-corrected QT (QTc) intervals showed significant variability corresponding to the frequency of episodes in a retrospective evaluation. The cessation of breastfeeding led to a termination of arrhythmias. The patient was temporarily equipped with a wearable cardioverter defibrillator vest, an implantable cardioverter defibrillator (ICD) was not implanted.

Discussion

The case report highlights the potential of self-recorded, patient-activated ECG monitoring in diagnosing recurrent palpitations, and the dilemma of timing for implanting ICDs in young patients with ventricular arrythmias (VTs). Additionally, it underlines the role of post-partum hormones in the susceptibility to ventricular arrhythmias, calling for further research of gender-specific, and pregnancy-associated arrhythmias.

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.

Sex differences in long QT syndrome

Long QT Syndrome (LQTS) is a rare, inherited channelopathy characterized by cardiac repolarization dysfunction, leading to a prolonged rate-corrected QT interval in patients who are at risk for malignant ventricular tachyarrhythmias, syncope, and even sudden cardiac death. A complex genetic origin, variable expressivity as well as incomplete penetrance make the diagnosis a clinical challenge. In the last 10 years, there has been a continuous improvement in diagnostic and personalized treatment options. Therefore, several factors such as sex, age diagnosis, QTc interval, and genetic background may contribute to risk stratification of patients, but it still currently remains as a main challenge in LQTS. It is widely accepted that sex is a risk factor itself for some arrhythmias. Female sex has been suggested as a risk factor in the development of malignant arrhythmias associated with LQTS. The existing differences between the sexes are only manifested after puberty, being the hormones the main inducers of arrhythmias. Despite the increased risk in females, no more than 10% of the available publications on LQTS include sex-related data concerning the risk of malignant arrhythmias in females. Therein, the relevance of our review data update concerning women and LQTS.

Exploring cardiac effects after oxytocin 2.5 IU or carbetocin 100 μg: A randomised controlled trial in women undergoing planned caesarean delivery

BACKGROUND

Oxytocin can stimulate release of myocardial biomarkers troponin I and T, prolong QTc and induce ST-depression.

OBJECTIVE

To explore cardiac changes after either intravenous carbetocin or oxytocin.

STUDY DESIGN

Exploratory phase 4 randomised controlled trial.

SETTING

Obstetrics units of Oslo University Hospital, Norway between September 2015 and May 2018.

PARTICIPANTS

Forty healthy, singleton pregnant women aged 18 to 50 years at gestational age at least 36 weeks with a planned caesarean delivery.

INVENTIONS

Participants were randomised to receive either oxytocin 2.5 IU or carbetocin 100 μg immediately after delivery.

MAIN OUTCOME MEASURES

The primary endpoint was the assessment of troponin I within 48 h of study drug administration. Troponin I and T, and creatine kinase myocardial band assessments were measured before spinal anaesthesia (baseline), and again at 4, 10 and 24 h after delivery. QTc, ST-depression and relative increase in heart rate were recorded from start of study drug administration to 10 min after delivery. All adverse events were monitored.

RESULTS

Compared with the carbetocin group, higher troponin I levels were observed in the oxytocin group at 4 h and 10 h after delivery. For both treatment groups, an increase from baseline in troponin I and T was most pronounced at 10 h after delivery, and it had begun to decline by 24 h. QTc increased with time after administration of both study drugs, with a mean maximum increase of 10.4 ms observed at 9 min (P  < 0.001). No statistical differences were observed in QTc (P = 0.13) or ST-depression (P = 0.11) between the treatment groups.

CONCLUSIONS

Oxytocin 2.5 IU and carbetocin 100 μg caused a similar increase in QTc. The trial was underpowered with regards to ST-depression and the release of myocardial biomarkers and these warrant further investigation. Data from this trial will inform a larger phase 4 trial to determine potential drug differences in troponin release.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02528136.

Mechanical QT and JT intervals by M-mode echocardiography: An extrapolation from the concurrent electrocardiographic tracings

Background

Congenital long QT syndrome (CLQTS) is a life-threatening ion channelopathy leading to syncope and sudden death. Early diagnosis during the prenatal period and timely intervention can prevent sudden cardiac death and catastrophic consequences of this genetic ion channelopathy. Fetal magnetocardiography and fetal electrocardiography (ECG) enable the measurement of fetal QT and JT intervals, but their inherently technically challenging and/or resource-intensiveness nature preclude their routine clinical application. On the other hand, the high-temporal resolution of M-mode echocardiography makes it a well-suited and widely available modality for the measurement of cardiac events.

Aims and Objectives

We aimed to investigate the mechanical counterparts of the electrical QT and JT intervals on M-mode echocardiographic images of the tricuspid, mitral and aortic valves, and aortic wall.

Methods

We performed a prospective study on consecutive children referred to the outpatient pediatric cardiology clinic at a tertiary children's hospital. We defined M-mode echocardiographic landmark points on tracings of tricuspid annular planar systolic excursion, mitral and aortic valves, and aortic wall with simultaneous electrocardiographic recording. We measured the mean±SD of the absolute time difference and RR-adjusted time difference in cases with non-coincident ECG events and echocardiographic landmarks.

Results

Fifty healthy children were enrolled in the study. In 47 (94%) out of the 50 children, Q was coincident with the starting point of the tricuspid annular plane systolic excursion. In all children, the Q was coincident with the mid-point of the A-C line of the mitral valve. In 38 (76%) cases, there was a bump on the anterior wall of the aortic root immediately before the change in the slope of the aortic wall. This was coincident with the Q wave in 100% of cases. In all cases, the J point coincided with the point of acceleration of velocity on TAPSE. In all children, the J point coincided with the initial maximal opening of the aortic cusps. The end of the T wave occurred coincident with the peak of the tricuspid annular planar systolic excursion in 47 children (94%). In 48 children (96%), the end of the T wave coincided with the aortic cusps' closure point.

Conclusions

Based on our findings, we propose to measure the averaged mechanical QT and JT intervals by using an angled M-mode tracing of the aortic and mitral valve in five consecutive beats in the parasternal long-axis view. This is the first study on mechanical QT and JT intervals in healthy children. The study opens the horizons into the in-utero diagnosis of congenital long QT syndrome by measuring fetal QT and JT intervals using the widely available M-mode echocardiography.

Sex Hormones and Repolarization Dynamics during the Menstrual Cycle in Women with Congenital Long QT Syndrome

BACKGROUND

Women with congenital long QT syndrome (LQTS) experience increased cardiac events risk after the onset of adolescence, perhaps stemming from the known modulating effects of sex hormones on the cardiac potassium channels.

OBJECTIVE

We hypothesized that the effect of sex hormones on cardiac ion channel function may modify ECG parameters associated with the propensity for ventricular tachyarrhythmias during the menstrual cycle in women with LQTS.

METHODS

We prospectively enrolled 65 women with congenital LQTS (LQT1 [N=24], LQT2 [N=20]) and unaffected female relatives [N=21]. Subjects underwent three 7-day ECG recordings during their menstrual cycles. Simultaneous saliva testing of sex hormone levels was obtained on the first day of each 7-day ECG recording cycle.

RESULTS

Mean age was 35±8 years, without a significant difference among the groups. In LQT2 women, linear mixed effects models showed significant inverse correlations of QTc with progesterone (p<0.001), and the progesterone to estradiol ratio (p<0.001). Inverse relationships of the RR interval with estradiol levels (p=0.003) and of the T-wave duration with testosterone levels (p=0.014) were also observed in women with LQT2. In contrast, no significant associations were observed between ECG parameters and sex hormone levels the women with LQT1 women or the unaffected relatives.

CONCLUSIONS

This is the first study to prospectively assess correlations between repolarization dynamics and sex hormone levels during the menstrual cycle in women with congenital LQTS. Our findings show genotype-specific unique QTc dynamics during the menstrual cycle that may affect the propensity for ventricular tachyarrhythmia in women with LQTS, particularly LQT2 women.

Prevalence and Risk Factors of QTc Prolongation During Pregnancy

Background

Prolonged QT intervals have been observed in pregnant women, which predispose them to a higher risk of potentially lethal ventricular arrhythmias. This study was designed to evaluate the prevalence of QTc prolongation in Chinese hospitalized parturient women with single and twin pregnancies, and to explore potential risk factors associated with QTc prolongation.

Methods

This retrospective study included 1,218 patients from a large Chinese population between January 2014 and October 2020. Data from parturient women with single and twin pregnancies without pre-pregnancy cardiac diseases were collected. QTc was corrected by the Fridericia formula [QTc = QT/RR(1/3)], and QTc ≥ 460 ms for females was defined as prolonged QTc, QTc ≥ 500 ms was defined as severely prolonged QTc. The prevalence and common risk factors of QTc prolongation during pregnancy were analyzed in this cohort. Uni- and multivariable logistic regression analysis were performed to identify clinical parameters associated with QTc prolongation in this population.

Results

The prevalence of QTc prolongation was 48.19% among this population, 10.56% in single pregnancy, 89.44% in twin pregnancies. The prevalence of severely prolonged QTc was 23.48% among the total cohort, 0.49% in single pregnancy, and 46.47% in twin pregnancies. The mean QTc interval was significantly longer in twin pregnancies than in single pregnancy (498.65 ± 38.24 vs. 424.96 ± 27.67 ms, P < 0.001). Systolic blood pressure, diastolic blood pressure, total cholesterol, serum uric acid, gestational hypertension and twin pregnancies were associated with QTc prolongation in parturient women.

Conclusion

This is the first study to assess the prevalence and risk factors of QTc prolongation between single and twin pregnancies. QTc prolongation is more prevalent, and QTc intervals are significantly longer in twin pregnancies as compared to single pregnancy.