Abstract
Implantable cardioverter-defibrillators have become standard preventive treatment for patients with ventricular arrhythmias and other life-threatening cardiac conditions. The advantages and efficiency of the device are supported by multiple clinical trials and outcome studies, leading to its popularity among cardiologists. Implantation of the device is not without adverse outcomes. Implantable cardioverter-defibrillator placement has been found to lead to negative psychological and psychosocial sequelae such as apprehension to engage in physical activity, chronic anxiety, decreased physical and social functioning, a nagging fear of being shocked by the device, and the development of “phantom shocks.” Defined as patient-reported shocks in the absence of evidence that the implantable cardioverter-defibrillator device has discharged, phantom shocks could impact the mental health of those affected. This article reviews the case of Mr. L, a 47-year-old man with ischemic cardiomyopathy who was seen by the psychiatry consultation team while under cardiologic care because he reported that his implantable cardioverter-defibrillator device had been shocking him despite no objective evidence after interrogating the device. A literature review of phantom shocks, their associated symptomatology, and psychological consequences are outlined and discussed.
Keywords
Introduction
The use of an implantable cardioverter-defibrillator (ICD) has played a pivotal role in treating patients at risk for life-threatening arrhythmias and other cardiac conditions. The device uses pacing and high-energy shocks to prevent and reduce potentially life-threatening arrhythmias by returning the patient’s heart to normal rhythmic functioning. Over the past 25 years, clinical trials have reported improved mortality with ICD treatment compared with usual care and/or medications.1,2 These results have led to wider use of the device.
Although there have been great improvements in the mortality of patients with an ICD, recent research has focused on patient-centered outcomes, such as quality of life, device acceptance, psychological and psychosocial well-being, and trauma reactions in research and clinical care.2,3 Currently seen as the standard of care because of its high success rate in preventing arrhythmias, ICD implantation has, however, also been associated with psychosocial distress, 2 mostly stemming from the patient’s apprehension of being suddenly shocked by the device. Shocks can be frightening and anxiety-inducing because they could be painful and occur without warning. 4 Patients frequently compare the impact of defibrillator shocks to being “kicked by a horse in the chest.”4,5
When this occurs, an ICD shock can be a traumatic experience,2,5 resulting in anxiety, fear, apprehension, and depression as well as other symptoms. These symptoms can lead the patients to engage in avoidance behaviors, reduce physical activities, social isolation, mood disturbances, and a reduced quality of life.6,7 Patients can also experience a phenomenon known as “phantom shocks.”
Phantom shocks are patients’ perception of having been shocked by an ICD without the device discharging. The currently estimated incidence is 5% to 9%.3,8 When first described in 1992, it was seen and attributed to the individual’s maladjustment to the ICD device—suggesting the need for the treatment of a secondary psychiatric disorder; additional case reports have suggested the use of antidepressants, anxiolytics, and/or participation in peer support groups to treat the condition. 3
We present the case of Mr. L, a 47-year-old man with ischemic cardiomyopathy and an implanted ICD who was seen by the inpatient psychiatry consultation service after he reported that he was being shocked by the ICD despite negative interrogation of the device. The cardiology service consulted the psychiatry team because Mr. L was experiencing significant distress and has had several admissions over the past few months (with the same chief complaint) without evidence of him being actually shocked by the device.
Case presentation
Chief complaints and symptomatology
Mr. L, age 47, is admitted to the cardiology service for the second time in less than two weeks. Ten days earlier, he was in a different hospital where his ICD was replaced. Mr. L had his first ICD for more than a decade and had not had any problems with it until 10 days ago, when he was walking down the street and he experienced a shock. His friends called the ambulance, and when he arrived at the hospital, the physicians told him that he needed a new device. Mr. L agreed. His doctors had warned him about the possibility of a shock many years ago, but he had put it out of his mind. He described the shock as terrifying. The doctors said the new device would help him, but Mr. L. felt his condition has gotten worse.
Mr. L says the new ICD has shocked him 27 times since then. He says it feels like a “horse is kicking me in the chest.” The doctors interrogated the device and reported that it has not discharged, but Mr. L says he knows that cannot be true. He says the shocks come at any time and out of the blue. Mr. L’s cardiologist requests a psychiatry consultation.
Mr. L tells the cardiologist, “I’m not crazy.” He has seen a psychiatrist in the past, and he is now convinced that the doctors are not listening to him, and he feels the cardiologists called the psychiatrist because they think he is losing his mind.
He has a history of psychiatric inpatient treatment when he was using cocaine daily. Even though he is annoyed, Mr. L calmly explains that he is sure that he is being shocked and no one can convince him otherwise. He explains that he has not been able to sleep because of the shocks. After prompting from his brother, Mr. L clarifies that he has been having difficulty sleeping since his wife died one year ago. He admits that he has been drinking alcohol to help him sleep and he has relapsed on cocaine after 14 years sober.
Mr. L says, “Maybe I am depressed.” His wife died unexpectedly, and he was not prepared. They had been married for 20 years, and she was the mother of five of his seven children.
Mr. L started using cocaine at the age of 20 and quit when he met his wife, who did not drink or use drugs. Mr. L struggled initially, but he had stopped using drugs and alcohol until his wife died. He denies suicidal ideation, but he said that he had lost his reason for living. He owns a small construction business. After his wife died, Mr. L. said he was stressed and could not cope, so he relapsed to cocaine. Mr. L has already been overwhelmed by the loss of his wife, and now the complications with his ICD are making life worse.
Discussion
Some patients who receive an ICD experience a “phantom shock” phenomenon. Although the pathophysiologic mechanism of this phenomenon is poorly understood, it is known that phantom shocks reported by the patient are indistinguishable from an objective shock. 5 This experience often leads to the evocation of alarm, frustration, and confusion, forcing patients to face uncertainties of an unpredictable, painful, confusing, and novel experience. 4
The data vary regarding the time after ICD implantation and the occurrence of phantom shocks. Prudente et al. 9 reported that approximately 70% of patients who reported phantom shocks had their device for more than two years. Swygman et al. 10 and Jacob et al. 11 reported that the phenomenon is more frequent in the first six months after implantation. Other researchers reported that phantom shocks are more frequent at night and in patients with depression and/or anxiety. 12 The phenomenon has been reported to be more likely to occur in patients who have had a previous ICD shock experience.9,11
Whether the higher levels of psychiatric symptomatology trigger the experience of phantom shock or vice versa remains to be elucidated. A 2012 retrospective study by Kraaier et al. 8 evaluated the incidence and predictors of phantom shocks in 629 patients with a history of ischemic or dilated cardiomyopathy and prior ICD implantation. In the primary prevention patient group identified, having a family member with a history of atrial fibrillation and New York Heart Association’s class higher than III were significant predictors of occurrence of phantom shocks, 8 with phantom shocks reported by 5.1% of ICD recipients. 8
No specific treatment regimen has been identified for phantom shocks. Several studies have attempted to address potential preventive approaches to the condition with mixed results. Berg et al. 3 aimed to assess a combined rehabilitation intervention, including exercise training and a psychoeducational component in patients treated with an implanted ICD. Their interventions included techniques for coping with the conditions that led to the ICD implantation as well as managing life with ICD, including the risk of shocks. Phantom shocks were also addressed in such a way to normalize the experience if it were to occur. The authors’ hypothesis was that the interventions would reduce occurrence of phantom shocks. However, although the measures were found to improve the patient’s overall mental health, they did not prevent phantom shocks.
Lewin et al. 13 designed the “ICD Plan” study to assess the use of cognitive-behavioral therapy (CBT) versus care as usual in managing and reducing the psychological impact of having an ICD device. Anxiety and depression were the primary outcomes. Results of this six-month study showed that patients in the ICD plan group had fewer physical limitations and reported a better quality of life. These patient’s anxiety and depression scores were improved, but the effect on the number of shocks or phantom shocks symptomatology were not statistically significant. In a similar study by Chevalier et al., 14 fewer shocks and lower reported anxiety were reported in the CBT group at 3- and 12-month assessment follow-up, with no difference in phantom shocks symptomatology.
Another phenomenon that has been previously approached is post-traumatic stress disorder (PTSD) associated with ICD placement. A 2011 review study by Sears et al. 15 reported that approximately 20% of phantom shock patients also had PTSD symptomatology, suggesting that electrophysiologists should develop a screening and referral mechanism for these patients similar to those developed for patients with PTSD symptoms due to other causes.
Treatment approach and case closure
In Mr. L’s case, he expressed concerns about his inability to sleep and complained of anxious symptoms. His presentation showed evidence of an untreated anxiety and depressive conditions, and he was diagnosed with adjustment disorder with mixed anxiety and depressed mood, and cocaine use disorder. Other differential diagnoses considered were substance-induced anxiety disorder, substance-induced mood disorder, acute stress disorder, anxiety secondary to a medical condition, major depressive disorder, and primary insomnia.
Treatment targeted his combined symptomatology (insomnia, anxiety, and depression) and mirtazapine—a tetracyclic piperazinoazepine with noradrenergic and serotonergic properties—was chosen for its pharmacological efficacy. With sedation as its most common side effect, this medication has shown efficacy for treating depression in patients with significant co-occurring anxiety and insomnia and for treating preoperative anxiety. This agent has no reported cardiac effects and reports of orthostatic hypotension are rare. Additionally, because of the multiple hepatic pathways used for metabolism, clinically significant drug–drug interactions are less likely to occur compared with other antidepressants. The treatment team did not discuss the unlikelihood of objective shocks occurring with the patient to limit additional patient distress.
Conclusion
Phantom shock can be a distressing, traumatic, and anxiety-provoking experience. Although its pathophysiology is being debated and a standardized treatment regimen is being identified, the symptoms reported by patients and their associated distress remain real to them. These symptoms can result in increased anxiety, low mood, and insomnia, among others. Mirtazapine, an antidepressant, was an effective pharmacotherapy for Mr. L resulting in complete resolution of his distressing symptoms. After approximately one week on the cardiology unit, Mr. L was discharged from the hospital to continue his care, including substance abuse treatment and psychopharmacological regimen (mirtazapine, 15 mg/d at bedtime) as an outpatient.
Footnotes
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.