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Abstract
The wearable cardioverter defibrillator (WCD) is becoming a more and more widely used instrument for the prevention of sudden cardiac death of patients either with a secondary prevention implantable cardioverter defibrillator indication or with a transient high risk of sudden cardiac death. Although clinical practice has demonstrated a benefit of protecting patients for a period as long as 3–6 months with such devices, the current European guidelines concerning ventricular arrhythmias and sudden cardiac death are still extremely restrictive in the patient selection in part because of the costs derived from such a prevention device, in part because of the lack of robust randomised trials.
To illustrate expanded use cases for the WCD, four real-life clinical cases are presented where patients received the device slightly outside the established guidelines. These cases demonstrate the broader utility of WCDs in situations involving acute myocarditis, thyrotoxicosis, pre-excited atrial fibrillation and awaiting staging/prognosis of a lung tumour. The findings prompt expansion of the existing guidelines for WCD use to efficiently protect more patients whose risk of arrhythmic cardiac death is transient or uncertain. This could be achieved by establishing a European register of the patients who receive a WCD for further analysis.
- Tachycardia, Ventricular
- Ventricular Fibrillation
- Acute Coronary Syndrome
- Telemedicine
- Out-of-Hospital Cardiac Arrest
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- Tachycardia, Ventricular
- Ventricular Fibrillation
- Acute Coronary Syndrome
- Telemedicine
- Out-of-Hospital Cardiac Arrest
Introduction
The wearable cardioverter defibrillator (WCD) has become an essential tool for managing patients at high risk of transient cardiac death. However, current European guidelines primarily focus on a specific and small population, leaving potential applications in various clinical scenarios largely unexplored.1 This article not only sheds light on real clinical cases that highlight the expanded benefits of WCDs but also introduces the proposal for a European register for patients receiving WCDs as a prophylactic measure, particularly in scenarios that deviate from the existing guidelines.
The current guidelines governing the prescription of WCDs focus primarily on individuals at a particularly high risk of sudden cardiac death due to specific clinical conditions.2 ,1 3–6 However, this approach overlooks a substantial number of patients who fall outside these narrow parameters yet could substantially benefit from WCD prophylaxis. By establishing a European register to document instances where WCDs are prescribed beyond the current guidelines, the medical community could gather valuable data that showcases the device’s effectiveness in varied clinical contexts.
We thereby propose a European register of patients receiving WCDs as a prophylactic measure to systematically collect data from diverse patient groups, healthcare professionals and researchers to gain a deeper understanding of the WCD’s efficacy in scenarios previously unexplored. This data-driven initiative has the power to bridge the gap between evidence and clinical practice, ensuring that patients receive the most suitable treatments irrespective of their divergence from existing guidelines.
The analysis of the European register could act as a catalyst for the revision and expansion of the current guidelines governing WCD prescription. The cumulative evidence amassed from patients with various risk profiles and conditions can provide a robust foundation for a more comprehensive set of guidelines that encompasses a wider patient spectrum. This evolution in guidelines could not only improve patient outcomes but also enhance the credibility of the medical community in addressing the diverse needs of patients across Europe.
Case descriptions
Case 1: WCD as bridge to ICD implantation during tumour staging and prognosis evaluation
A 66-year-old man was brought to our emergency department after undergoing cardiopulmonary resuscitation at home due to a sudden cardiac arrest. The underlying cause of the cardiac arrest was initially unclear. The patient’s medical history revealed hypertension as the only significant cardiovascular risk factor. He did not have a history of previous cardiac events, and there was no family history of sudden cardiac death. To determine the cause of the cardiac arrest, a comprehensive diagnostic workup was performed. Cardiac MRI revealed evidence of acute myocarditis, which could have been the underlying trigger for the cardiac arrest.7 The patient was managed with appropriate medications and close cardiac monitoring.
However, during the cardiological diagnostic assessments, a CT indicated the presence of a bronchial carcinoma. This new diagnosis added complexity to the patient’s clinical picture and required further evaluation and management. Considering the acute myocarditis diagnosis and the uncertainty regarding the bronchial carcinoma’s prognosis, a multidisciplinary approach was adopted. Given the patient’s secondary prophylactic indication for an implantable cardioverter defibrillator (ICD) due to the cardiac arrest, the decision was made to implement a temporary WCD as a bridging therapy during the initial phase of the lung carcinoma staging and management. The patient underwent a thorough tumour staging assessment, and based on the results, a treatment plan involving a combination of chemotherapy and radiotherapy was initiated for bronchial carcinoma. The prognosis was initially uncertain. After approximately 4 months of oncological treatment and close monitoring, the prognosis for the bronchial carcinoma was established to be over 1 year. With this information, the decision was made to proceed with an implantation of a subcutaneous ICD for the patient’s secondary prophylactic indication.
Added value of this case—temporary and minimally invasive protection with WCD against sudden death while prognosis of cancer is established.
Case 2: WCD in thyrotoxic cardiac disease with transient high arrhythmic cardiac death risk
A 53-year-old man presented to the emergency department with acute heart failure symptoms, including difficulty breathing, lower leg oedema and tachycardic atrial fibrillation with a heart rate of 200 beats per min. Physical examination revealed hyperthermia. The initial left ventricular ejection fraction (LVEF) during atrial fibrillation was severely reduced at 15%. Laboratory results indicated marked hyperthyroidism, consistent with a thyrotoxic crisis. Subsequent workup confirmed Graves disease as the underlying cause. The patient was urgently treated with thyreostatic therapy, leading to stabilisation over several days. Despite the normalisation of heart rate, multiple non-sustained ventricular arrhythmias were observed during patient monitoring. A complete cardiological evaluation was hindered due to acute contraindication to dye infusion for coronary angiography and the relative tachycardia of the patient, which precluded cardiac—synchronisation of the cardiac MRI. Considering the transient high risk for cardiac arrhythmias including ventricular tachycardias (VTs),8 a wearable cardioverter defibrillator (WCD) was prescribed until the normalisation of thyroid function tests and completion of the cardiological workup. The WCD would provide protection from life-threatening arrhythmias without the need for implantation. After 1 month of wearing the WCD, the patient experienced an episode of tachycardic atrial fibrillation, with pseudoregularisation resulting in syncope, and subsequent therapeutic shock delivered by the WCD (figure 1). After 2 months of WCD use, thyroid function tests were normalised, allowing for the completion of the cardiological workup. Coronary angiography ruled out coronary artery disease, and cardiac MRI demonstrated no evidence of scars. The LVEF had improved to 40%. Further optimisation of heart failure therapy was undertaken. As the patient’s condition had improved, he could be discharged without the need for a permanent ICD. The WCD was no longer required, and he was closely monitored in an outpatient setting.
Recording of the werable cardioverter defibrillator during tachycardic atrial fibrillation with pseudoregularisation differential diagnosis ventricular tachycardia, then organising in a tachycardia with haemodynamic instability and adequate shock delivery and subsequent normalisation of the heart rhythm with recovery of consciousness of the patient.
Added value of this case—new risk of sudden death in thyrotoxicosis leading shock terminating lethal arrhythmia
Case 3: pre-excited atrial fibrillation and pending ablation
A 63-year-old patient was brought to the emergency department following an episode of sudden palpitations after a domestic altercation. On arrival of the first responder emergency doctor, he showed a wide complex tachycardia leading to a differential diagnosis between a VT and tachycardic atrial fibrillation with bundle branch block. Intravenous amiodarone was administered, resulting in symptomatic relief. The patient could be transported to our emergency department, where subsequent evaluation revealed atrial fibrillation with signs of pre-excitation, indicating the presence of an accessory pathway. Further ECG analysis localised the accessory pathway to a left posteroseptal position. Echocardiography demonstrated normal biventricular function. Given the patient’s history of chronic coronary heart disease, and because of evidence of recurrent episodes of non-sustained ventricular arrhythmias during cardiological monitoring, the decision was made to proceed with coronary angiography, revealing severe three-vessel disease. Stenting of the right coronary artery was performed, followed by staged stenting of the left anterior descending artery and circumflex artery as coronary artery bypassed was refused by the patient. Dual antiplatelet therapy was initiated post stenting, with plans to continue uninterrupted for at least 3 months. Due to the documented pre-excited atrial fibrillation and the need to delay ablation for 3 months, the patient was fitted with a WCD, despite the normal biventricular function. This measure aimed to provide protection from arrhythmia-related complications. After 15 days of wearing the WCD, a new episode of pre-excited atrial fibrillation occurred. The WCD alarm activated, allowing the patient to prevent a shock by pressing the response buttons (figure 2). Rate control therapy with amiodarone was initiated to manage the atrial fibrillation. The patient’s heart rate was stabilised with amiodarone, and he was discharged with instructions to continue wearing the WCD until his scheduled ablation. Regular follow-up appointments were scheduled to monitor his progress and adjust treatment as needed and an ablation of the left accessory pathway and atrial fibrillation was scheduled in 3 months.
Recording of the wearable cardioverter defibrillation during episodes of pre-excited atrial fibrillation and atrial tahcycardia with no shock delivery from the device because of action taken by the patient in pressing the response button after the alarm. FB: Front-back, SS: side-side.
Added value of this case—protected with WCD, but monitoring changed medical therapy.
Case 4: WCD in idiopathic VT
A 60-year-old woman presented to our hospital with a history of recurrent episodes of palpitations and dizziness. She had a medical history of hypertension, but no known cardiac structural abnormalities. Her symptoms had been escalating recently, prompting her to seek medical attention. On the day of presentation, she called emergency services due to a particularly prolonged episode of palpitations that did not spontaneously resolve. On arrival, an ECG performed by the emergency physician revealed a wide complex tachycardia with a heart rate of 170 beats per minute. The tachycardia did not respond to adenosine administration, suggesting a ventricular origin. While en route to the hospital, the ventricular arrhythmia spontaneously terminated. Subsequent ECG analysis demonstrated a monomorphic VT with an inferior axis, accompanied by a left bundle branch block pattern. The R/S transition was noted in precordial leads V3/V4, suggesting a potential origin from the right ventricular outflow tract (RVOT) or left ventricular outflow tract. Initial evaluation during the hospital stay included a comprehensive cardiological assessment, involving a normal echocardiogram, unremarkable coronary angiography and a normal cardiac MRI scan. Given the absence of structural cardiopathy and the recurrent nature of the VT, an idiopathic VT was diagnosed. The decision was made to pursue catheter ablation as a definitive treatment. However, due to the scheduling constraints of the electrophysiology team, and the will of the patient not to be transferred to another hospital, it was deemed appropriate to discharge the patient with a WCD for secondary prevention until the ablation could be performed. After a 2-week interval, the patient returned for the planned catheter ablation procedure. The procedure successfully identified a focal origin of the VT emanating from the posterobasal region of the RVOT. On the following day, the patient was discharged with a prescription for flecainide as a maintenance antiarrhythmic medication. Her need for a WCD was obviated, and no intracardiac defibrillator was deemed necessary. The treatment plan involving catheter ablation and subsequent medication administration led to the resolution of her symptoms and improved quality of life.
Added value of this case—patient had an unclear risk of sudden death due to idiopathic VT, WCD offered efficient protection without surgery while the patient was treated and risk was eliminated. No long-term negative effects.
Review of the literature
We assessed the existing European and American guidelines concerning the current indications for the use of the WCD.
The European guidelines for heart failure issued in 20214 and the guidelines for ventricular arrhythmias from 20221 both provide recommendations for the utilisation of the WCD. For heart failure, these guidelines propose its usage as a class IIb/B intervention for patients with reduced ejection fraction, both those with ischaemic and non-ischaemic cardiopathy, on their initial diagnosis. Similarly, in the context of ventricular arrhythmias, the guidelines suggest a class IIb/B usage for patients post myocardial infarction that show a severely impaired LVEF.
The American guidelines (American Heart Association/American College of Cardiology/Heart Rhythm Society Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death from 20175 and those from heart failure from 20166) also propose the application of WCD in certain scenarios.9 In the case of heart failure, patients with ischaemic conditions and severely reduced ejection fraction within 40 days of a myocardial infarction, as well as patients with newly diagnosed non-ischaemic dilated cardiomyopathy, during the initial months of optimised therapy initiation, fall under a class IIb indication. Additionally, a class IIa/B indication is given for patients undergoing removal of an ICD as a temporary measure until a new device can be implanted.
It is important to note a difference between the USA and Europe regarding the use of WCD on paediatric patients; it is allowed in the US but not in Europe.
In Germany, the DGK (German Cardiac Society) has issued a position paper10 that designates a class I indication for WCD use in patients after ICD explantation. For other cases, a class II indication is maintained. This paper also permits clinicians to consider WCD usage in special cases such as haemochromatosis, amyloidosis and toxic cardiomyopathies.
An important reference to the recent literature is the ANMCO (Associazione nazionale medici cardiologi) position paper,11 which guides Italian clinicians in the appropriate utilisation of WCD in clinical practice. This paper advocates for a broader implementation of the device, encompassing a wider spectrum of patients with severely reduced LVEF, including both ischaemic and non-ischaemic cases. It also establishes guidelines and timelines for WCD usage in various conditions like Takotsubo cardiomyopathy, alcoholic cardiomyopathy, toxic cardiomyopathy, sarcoidosis, peripartum cardiomyopathy, myocarditis and tachycardiomyopathy
Discussion
The presented cases highlight the underexplored utility of WCDs beyond the existing guidelines for transient cardiac death risk. The conventional guidelines emphasise specific patient profiles, such as those with reduced ejection fraction and heart failure. However, these real-life clinical cases demonstrate the potential benefits of extending WCD use to patients with different underlying conditions, such as bridging the time to an oncological prognosis evaluation, thyrotoxicosis-induced arrhythmias and pre-excited atrial fibrillation. While not all cases demonstrate therapy delivered by the WCD, they do emphasise the significance of preventing sudden cardiac death across a wider range of patients. This aspect is not consistently addressed in the current European and American Guidelines for heart failure, ventricular arrhythmias and sudden cardiac death. Moreover, the WCD can function as a monitoring tool for patients at a high risk of arrhythmias, allowing for further refinement of antiarrhythmic therapy during the transitional phase. The clinical cases also illustrate how judicious patient selection can mitigate inappropriate shocks, as the WCD may not always accurately identify VTs. However, patients have the ability to prevent shocks by using the response button (eg, during rapid atrial fibrillation in case 3).
The use of WCDs in these cases serves as a temporary bridge, providing critical protection during periods of heightened risk, pending further evaluation or intervention. This broader application of WCDs could potentially lead to improved patient outcomes, reduced instances of sudden cardiac death and enhanced patient quality of life.
Conclusion
Our research strongly advocates for the establishment of a comprehensive European register dedicated to patients receiving a WCD. This initiative aims to meticulously scrutinise cases falling beyond or at the periphery of existing guidelines. By doing so, we aspire to broaden the scope of the next European guidelines, ensuring broader accessibility to WCDs for individuals at heightened risk of sudden cardiac death.
Moreover, the implementation of this European register holds the promise of illuminating scenarios characterised by underappreciated risks of ventricular arrhythmias, notably observed in cases of take-tsubo cardiomyopathy and thyrotoxicity. This strategic undertaking not only expands access to life-saving interventions but also offers invaluable insights into mitigating ventricular arrhythmias in hitherto overlooked clinical circumstances.
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Footnotes
Contributors The authors jointly contributed to the manuscript. The first author conceived the original idea and made significant contributions to the drafting and revision of the article. All authors have equally contributed to the development, drafting and critical revision of the manuscript, and have approved the final version for submission.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.