Usage of the wearable cardioverter-defibrillator during pregnancy.

Background: Pregnancy can trigger or aggravate the risk for life-threating arrhythmias in cardiac diseases. Pregnancy is associated with reluctance for implantable cardioverter-defibrillators (ICD) due to concerns about radiation. Thus, the wearable cardioverter-defibrillator (WCD) might be an option during pregnancy. Aim of the study was to collect experiences about the use of WCD in pregnancy. Methods and results: This study retrospectively included eight women who received a WCD during pregnancy. They suffered from ventricular tachycardia (VT) without known cardiac disease (n = 3), Brugada syndrome (n = 1), hypertrophic cardiomyopathy (n = 1), dilated cardiomyopathy (n = 1), non-compaction (n = 1), and survived sudden cardiac arrest during a preceding pregnancy (n = 1). WCD usage was started between 13 and 28 weeks of gestation. WCD wearing period ranged from 3 days to 30.9 weeks, WCD wearing time ranged from 13.0 to 23.7 h per day. Two women (25%) abandoned WCD already during pregnancy. Neither appropriate nor inappropriate WCD shocks were recorded. Antiarrhythmic management included beta-blockers (n = 5) and flecainide (n = 2). After delivery, ICD were implanted (n = 4), refused (n = 2) and estimated not necessary after successful catheter ablation (n = 2).
Conclusion: Uneventful pregnancy is possible in women at risk for sudden cardiac death by interdisciplinary monitoring and diligent pharmacotherapy protected by the WCD. Since no WCD shocks were recorded, the effectiveness of WCD during pregnancy is still unclear. However, arrhythmia detection by WCD was very good despite the changed anatomy in pregnancy. Nevertheless, further studies are necessary to assess effectiveness of WCD in pregnant women. Furthermore, efforts should be made to increase the wearing adherence of WCD during pregnancy.

Introduction

Pregnancy in women with inherited or acquired heart disease represents a challenge for both cardiologists and obstetricians. Limited evidence in this specific group exists as women during pregnancy and childbirth had usually been excluded from participation in clinical trials, and thus, recommendations for the treatment of pregnant women with cardiovascular diseases are based only on expert opinion [1].

Pregnancy is associated with an increased vulnerability for fatal arrhythmias [2], [3], [4]. Ventricular tachyarrhythmias in hypertrophic (HCM), dilated (DCM), restrictive (RCM) and arrhythmogenic right ventricular cardiomyopathy (ARVC) and non-compaction (NCCM), can be triggered or aggravated during pregnancy [5], [6], [7], [8], [9]. Implantable cardioverter-defibrillators (ICD) improve survival in patients with life-threating cardiac arrhythmias. ICD implantation, however, is associated with risks like lead-associated thrombosis, infection and ventricular perforation [10]. ICD implantation during pregnancy has been reported in several cases [11], [12]. Due to the necessity for radiation and anesthesia, there are, however, concerns about the procedure during pregnancy.

The wearable cardioverter-defibrillator (WCD; LifeVest, ZOLL, Pittsburgh, USA) was introduced for temporary prevention of sudden cardiac death (SCD). It is used in patients in whom the risk for SCD is expected to be only temporarily or if ICD implantation is unsuitable [13], [14]. During pregnancy, the WCD is a therapeutic option if a cardiac disease with susceptibility to arrhythmias is diagnosed or if there is deterioration of left ventricular ejection fraction (LVEF). So far, experiences with WCD have been reported mainly from women with peripartum cardiomyopathy (PPCM) in the post-delivery period [15], [16], [17], [18]. To our knowledge, application of a WCD during pregnancy has been reported only from 13 patients with PPCM, whose clinical details, however, are not reported and from a patient with NCCM who refused an ICD [7], [18].

Because of limited experiences with WCD during pregnancy, we report of eight pregnant women who have been temporarily equipped with a WCD.

Methods

In this bi-national multi-center retrospective case series, patients who received a WCD during pregnancy were included. Patients having received the WCD only after delivery were excluded. We contacted clinics in Germany and Austria with experience with the WCD by mail and telephone. If they had experience in managing pregnant women with a WCD between 01/2015 and 12/2021, these centers were invited to participate.

Data were collected retrospectively according to a preset questionnaire (Table S1, supplemental material) by the local participants and analysed in the department of cardiology at the university hospital in Regensburg.

All women remained under cardiologic, obstetric and anaesthesiologic monitoring during pregnancy and delivery, including echocardiography, ECG monitoring, assessment of pharmacotherapy, gynaecological investigations and early planning of delivery. All patients were instructed to wear the WCD continuously. The following arrhythmic events were registered with the remote monitoring system of ZOLL Patient Management Network: non-sustained ventricular tachycardia (nsVT), sustained ventricular tachycardia (VT) and ventricular fibrillation (VF). The LVEF was monitored by 2D-echocardiography.

Patients were followed up after delivery for the period of WCD therapy or for minimum two weeks.

The study was conducted in accordance with the Declaration of Helsinki and data analysis was approved by the local ethics committee of the university hospital in Regensburg.

All statistical analyses were performed using commercially available statistical software IBM SPSS Statistics Version 26.0.

Results

A total of 128 clinics throughout Germany and Austria were contacted. A response was received from 112 clinics (87.5%), and eight patients with WCD therapy during pregnancy from three German centers (four patients from Hannover Heart Rhythm Center, Department of Cardiology and Angiology, Hannover Medical School, Hannover, Germany, one patient form Department of Cardiology, University Hospital of Regensburg, Regensburg, Germany and one patient from Department of Cardiology, University Hospital of Freiburg, Freiburg, Germany) and one Austrian center (two patients from Department of Internal Medicine II, Division of Cardiology, Medical University of Vienna, Vienna, Austria) were included. One of the patients (patient 7) has been previously published [7]. Initiation of WCD usage was between 05/2015 and 06/2021.

Baseline characteristics

Baseline characteristics are shown in Table 1. All women became pregnant by spontaneous conception. Four patients (patients 1, 4, 6 and 7) were already suffering from known cardiac disease before pregnancy, as listed in Table 1. A further woman (patient 2) had been resuscitated because of cardiac arrest due to VF/VT in the course of a previous pregnancy five years before. In that woman, emergency cesarean section at 30 weeks of gestation (GW) had been carried out. Transthoracic echocardiography und cardiac computed tomography did not show any abnormal findings. Since the patient refused further investigations including magnetic resonance imaging of the heart, and idiopathic VF/VT was assumed. The further three patients (patients 3, 5 and 8) had no known pre-existing cardiac diseases with elevated risk for ventricular tachyarrhythmias but presented sustained VTs during their first months of pregnancy. In patient 3 the diagnosis of cardiac sarcoidosis was established only after delivery.

Table 1

Baseline characteristics and indication for WCD usage during pregnancy.

	Patient 1	Patient 2	Patient 3	Patient 4	Patient 5	Patient 6	Patient 7	Patient 8
Age at the beginning of pregnancy (years)	27	24	36	36	40	34	27	36
Parity (n)/Abort (n)	0/0	1/0	0/0	0/0	0/0	0/0	0/0	1/1
Pre-existing cardiac diseases	Brugada syndrome	none	none	HCM	none	DCM	NCCM	none
Arrhythmias before pregnancy	0	VF and VT	0	0	0	0	0	0
Pre-existing non-cardiac diseases:
- Arterial hypertension	0	0	yes	0	0	yes	0	yes
- Type 1 diabetes	0	0	0	0	0	yes	0	0
- Adiposity	0	0	yes (BMI 35.9)	0	0	yes (BMI 33.7)	0	yes (38.3)
LVEF at beginning of pregnancy (%)	≥60	≥60	50	≥60	≥60	34	49	66
Indication for WCD	Brugada syndrome, bridging to ICD	Previous VF and VT, bridging to ICD	Sustained VTs despite therapy with flecainide and bisoprolol, bridging to VT ablation and ICD	HCM with nsVTs, bridging to ICD	Sustained VT, bridging to VT ablation	DCM with severely reduced LVEF < 35%, bridging to ICD	NCCM with decrease of LVEF and nsVTs, bridging to ICD	Sustained VT, bridging to VT ablation

BMI, body mass index; DCM, dilated cardiomyopathy; HCM, hypertrophic cardiomyopathy; ICD, implantable cardioverter defibrillator; LVEF, left ventricular ejection fraction; NNCM, non-compaction; nsVT, non-sustained ventricular tachycardia; VF, ventricular fibrillation; VT, ventricular tachycardia; WCD, wearable cardioverter/defibrillator.

Three women had additional cardiovascular risk factors, as listed in Table 1.

WCD indication, pharmacotherapy and course of the pregnancies

Primary preventive protection by WCD was recommended in patient 1 with Brugada syndrome and increased risk for ventricular arrhythmias, patient 4 with HCM and nsVTs in Holter ECG, patient 7 with NCCM, nsVTs during Holter monitoring and decrease of LVEF from 49% to 38% during the second trimenon of pregnancy and patient 6 with DCM and severely reduced LVEF of 34% at the beginning of pregnancy (Table 1). Three further patients (patients 3, 5 and 8) presented with sustained VTs during their first months of pregnancy and were thus equipped with WCD. Patient 3 presented with scar-related VT. The other two women showed idiopathic VTs from the outflow tract. Patient 2 with cardiopulmonary resuscitation because of cardiac arrest during a preceding pregnancy received the WCD as secondary prevention (Table 1).

In addition to WCD usage, patients 3–7 received antiarrhythmic medication, as listed in Table 2A.

Table 2

Pregnancy and delivery in patients with WCD usage during pregnancy.

	Patient 1	Patient 2	Patient 3	Patient 4	Patient 5	Patient 6	Patient 7	Patient 8
(A) Pregnancy
LVEF at initiation of WCD use (%)	≥60	≥60	50	≥60	≥60	34	38	66
GW at WCD initiation	28	13	16	14	28	15	25	19
Cumulative WCD wearing (weeks)	15.1	21.3	24.9	17.7 (refused further wearing)	22.9	0.4 (refused further wearing)	15.6	30.9
WCD wearing per day (hours)	13 0.0	22.0	data missing	17.8	23.7	14.0	21.1	23.1
Cardiac medication during pregnancy	0	0	yes	yes	yes	yes	yes	yes
- Beta-blockers	0	0	bisoprolol5 mg/d	bisoprolol10 mg/d	metoprolol 190 mg/d	metoprolol 190 mg/d	bisoprolol5 mg/d	0
- Other antiarrhythmic drugs	0	0	flecainide300 mg/d	0	flecainide 200 mg/d	0	0	0
- Other antihypertensive drugs	0	0	0	0	0	methyldopa 1500 mg/d	0	methyldopa 500 mg/d
Other medication during pregnancy	0	0	0	0	potassium 80 mmol/d	insulin	enoxaparin 4000 IE/d	levothyroxine
(B) Delivery
GW at delivery	38	32	39	39	39	34	37	39
Complications during delivery	0	0	0	0	0	0	0	0

GW gestational week; LVEF, left ventricular ejection fraction; WCD, wearable cardioverter/defibrillator.

WCD usage was started between GW 13 and 28. Median cumulative WCD wearing time was 19.5 weeks (range 3 days to 30.9 weeks). Median daily WCD wearing time was 21.1 h (range 13.0–23.7 h). Three patients had a wearing adherence of <20 h/day, and two of them eventually refused the WCD because of personal reasons. In spite of intensive patient education, one woman (patient 6) was not aware of the possible consequences of their decision or rather she did not want to admit the possible consequences. Despite repeated enquiries, no detailed information about the reasons for discontinuation of the other patients were retrospectively obtained.

Neither appropriate nor inappropriate WCD shocks occurred. Patient 8 showed VTs from the right ventricular outflow tract (RVOT) which were haemodynamically tolerated, therefore no WCD shock was necessary. The patient stopped the shock-delivery with the response button and the detected VT terminated spontaneously. Because of haemodynamically well tolerated VTs and the patient's preference there was no clinical consequence of this event during pregnancy. Patient 3 had a scar-related VT (most likely due to the cardiac sarcoidosis diagnosed after delivery) which was haemodynamically tolerated, therefore no WCD shock was necessary. The patient stopped the shock-delivery with the response button and the VT terminated spontaneously. As consequence of this event, the dosage of flecainide was increased and the shock-delivery threshold of the WCD was changed from >180 to 200 beats per minute.

Additionally, in patients 4 and 7 nsVTs were recorded by the WCD. Especially, patient 7 showed recurrent nsVTs with maximum 22 consecutive ventricular beats.

All these VTs and nsVTs were correctly detected by the WCD. In patient 8 artefacts led to a warning signal prior to administration of a shock. Shock-delivery was stopped with the response button. All other artefacts or supraventricular tachycardias were properly detected by the WCD and did neither result in a warning signal nor in an inappropriate shock.

No patient developed any pregnancy complication, like gestosis, coagulation abnormalities and infections. Only patient 1 developed a gestational diabetes.

Delivery and follow-up

All women gave birth by cesarean section at a time when the medical staff of all involved departments was present (Table 2B). No arrhythmia occurred during delivery.

Postpartum echocardiography showed no deterioration of systolic function in women with previously normal or just slightly reduced LVEF. LVEF of the patient with DCM (patient 6) decreased further, as shown in Table 3 and remained severely reduced. LVEF of a woman with NCCM (patient 7) improved to pre-pregnancy conditions during the first month after delivery.

Table 3

Postpartum period in patients with WCD usage during pregnancy.

	Patient 1	Patient 2	Patient 3	Patient 4	Patient 5	Patient 6	Patient 7	Patient 8
LVEF after delivery (%)	≥60	≥60	50	≥60	≥60	26	46	66
WCD wearing time after delivery (weeks)	4.9	2.0	2.6	refused (already during pregnancy)	11.9	refused (already during pregnancy)	4.0	10.7
Significant arrhythmias after delivery	0	0	VTs	0	0	0	0	VTs
ICD implantation	4.9 weeks after delivery	2.0 weeks after delivery	2.6 weeks after delivery	14.9 weeks after delivery	0	0, refused	0, refused	0
Catheter ablation	0	0	2.0 weeks after delivery	0	7.9 weeks after delivery	0	0	10.7 weeks after delivery

ICD, implantable cardioverter defibrillator; LVEF, left ventricular ejection fraction; WCD, wearable cardioverter/defibrillator.

One woman (patient 2) suffered from an infection (a pilonidal cyst abscess with the need for surgical therapy) in childbed.

Median WCD wearing after delivery was 4.5 weeks (range 2.0–11.9 weeks). Four of the eight women (patients 1–4) consented with implantation of an ICD after delivery. In patients 5 and 8, ICD implantation was no longer necessary after a successful catheter ablation of VTs. Implantation of an ICD was recommended but declined in the patient with NCCM and recurrent nsVTs (patient 7) and the patient with DCM and severely reduced LVEF (patient 6). No patient died during a follow-up period of 2.0–11.9 weeks postpartum.

Newborns

Clinical data were available from six of the eight newborns. Among them, only the neonate of the woman with DCM (patient 6) showed a reduced Apgar score with 7/8/8. More detailed characteristics of the newborns are listed in Table S2 (supplemental material).

Discussion

This retrospective study of WCD usage during pregnancy of women with an increased arrhythmic risk shows that all eight women had an uneventful pregnancy and delivery under close monitoring. In none of the patients an appropriate or inappropriate WCD shock occurred during pregnancy, delivery or after delivery. In two of the eight patients haemodynamically well tolerated VTs were recorded during pregnancy, but in both cases shock-delivery was stopped by the response button and VTs terminated spontaneously. Only in one case artefacts led to a warning signal prior to administration of a shock. Fortunately, shock-delivery was stopped with the response button. All other artefacts, supraventricular tachycardias and nsVTs were properly detected by the WCD and did not cause any inappropriate warning alarm. No ventricular arrhythmias were recorded during delivery. Daily WCD wearing time was between 13.0 and 23.7 h (median daily WCD wear time 21.1 h).

The use of the WCD during pregnancy has numerous advantages over ICD implantation.

In seven of the eight women, this was the first pregnancy with an initial diagnosis of a cardiac disease or aggravation of pre-existing cardiac disease during pregnancy. Therefore, bridging by a WCD until ICD implantation or catheter ablation of VTs scheduled soon after delivery was considered as necessary. Thus, WCD is useful to protect pregnant women in whom ICD implantation or catheter ablation needs to be postponed to avoid exposure to radiation and anesthesia during pregnancy.

WCD can also be used to protect women with only temporary increased risk for malignant arrhythmias, e. g. by a temporary decrease of LVEF occurring during pregnancy or changes in ECG during PPCM [19]. The physiological haemodynamic changes during pregnancy and cessation of heart failure medication may lead to a worsening of LVEF during pregnancy in women with preexisting cardiomyopathy. After delivery LVEF may recover under improved heart failure medication. Thus, WCD prescription can avoid untimely ICD implantation if LVEF improvement can be expected.

WCD usage in non-pregnant patients with newly diagnosed heart failure is already popular to avoid untimely ICD implantation [13], [14], [20], [21], [22], [23], [24]. A relevant proportion of patients with newly diagnosed heart failure shows improvement of LVEF after initiation and optimization of heart failure therapy [21], [24] and also during long-term follow-up [20] according to underlying etiology [25]. Such a LVEF improvement can be expected in young women after delivery as well.

By the WCD-based remote rhythm monitoring, an interdisciplinary medical care could be facilitated. Furthermore, the WCD allows calculation of the heart rate variability (HRV). Although not addressed in our study, the HRV has been identified as an independent predictor for LVEF improvement [26]. Especially postpartum this could be a clinically relevant information to obviate untimely ICD implantation.

There are also relevant limitations of WCD usage in pregnancy.

One drawback of WCD usage is the dependence of protection against SCD from wearing adherence. Daily WCD wearing time of the eight women was similar or somewhat less than reported in the literature from non-pregnant patients [18], [27], [28], [29], [30], [31]. The daily WCD wearing time varies depending on the patient group and decreases over time [30], [31]. In our study three of eight women had a reduced wearing adherence of <20 h/day and two of them (25%) eventually refused the WCD already during pregnancy despite intensive patient education regarding possible medical consequences. Due to the retrospective character of the study, unfortunately, no detailed information about the reasons for discontinuation was obtainable. In studies with non-pregnant participants 8 – 14% stopped wearing the WCD prematurely due to issues with comfort or adverse reactions [30]. Additionally, in a study of women with heart failure, the proportion of patients with discontinuation of WCD usage because of nonadherence or device discomfort was high: 14% among the women with PPCM and 8% among women with dilated cardiomyopathy [18]. In further studies with non-pregnant patients it was shown that WCD use can negatively affect various quality of life measures (e. g. mental health, usual activities and mobility) [30], [32]. However, in another study, an improvement in depression scores was found during WCD usage [30], [33]. Whether the high WCD-refusal rate in pregnancy may be due to the increase of abdominal girth is uncertain because six of our patients (75%) wore the WCD until delivery. Hence, in the majority of the patients the physical body changes during pregnancy did not seem to be an obstacle. When using the WCD in pregnancy, efforts should be made to increase the wearing adherence.

The effectiveness of the WCD was already shown in numerous studies, including patients with newly diagnosed heart failure with severely reduced LVEF [13], [20], [23], and women with PCCM [14], [15], [22].

Application of WCD in pregnancy has, so far, only been reported in few cases [7], [18]. In none of them, neither appropriate nor inappropriate WCD shocks have been reported. In our study all women had an incidence-free pregnancy and delivery without an appropriate or inappropriate WCD shock. This may be due to close interdisciplinary monitoring and additional diligent pharmacotherapy in five of eight women. Pharmacotherapy makes a decisive contribution to reducing ventricular tachyarrhythmias [1]. Thus, the safety and effectiveness of WCD during pregnancy remains unknown, and the results of our study cannot resolve these concerns. We can only report that almost all arrhythmias were correctly detected despite the changed anatomy in pregnancy. Especially, all VTs were detected and resulted in a warning signal prior to shock-delivery. Since the VTs were hemodynamically well tolerated, shock-delivery was prohibited by response button. Artefacts were misinterpreted by the WCD only in one case. In this case the women stopped the shock-delivery. Any other artefacts, supraventricular arrhythmias or nsVTs led to inappropriate warning signals or WCD shocks.

In addition, the influence of WCD shocks on the fetal outcome is unclear. In contrast, effectiveness and safety of ICD shocks in pregnancy were already shown in several studies [34], [35], [36]. These reports, found no increased risk for adverse fetal outcomes following the occurrence of ICD shocks [35], [36], [37], [38], [39], [40]. Similar results can be expected for WCD shocks, but further studies are necessary.

Our study has several limitations. First, the study design and data collection were retrospective. Second, the number of patients was low and only six of the eight patients completed pregnancy with the WCD. Third, our cohort was heterogenous. Women were supplied with a WCD because of different diagnoses. Fourth, we cannot provide data on the effectiveness of WCD shocks during pregnancy since neither appropriate nor inappropriate shocks occurred. Fifthly, WCD recording data of one woman are incomplete. Sixthly, detailed reasons for discontinuation in 25% of the patients were not obtainable.

Conclusion

Uneventful pregnancy and delivery are possible in women at risk for life-threatening arrhythmias by early diagnosis, interdisciplinary monitoring and pharmacotherapy protected by the WCD.

Almost all arrhythmias (including VTs, nsVTs and supraventricular tachycardias) were correctly detected by the WCD. Only in case of one artefact it was necessary to stop the shock-delivery by response button. No inappropriate WCD shocks occurred. This indicates an adequate WCD monitoring function in pregnancy despite the changed anatomy. Our data, however, provide no information about the effectiveness of the WCD. Efforts should be made to increase the wearing adherence of WCD in pregnancy.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.