Should Sedative Administration Be Recommended as an Antiarrhythmic Therapy to Suppress Ventricular Fibrillation and Ventricular Tachycardia in Patients With Electrical Storm?　― A Scoping Review ―

Abstract

Background

Electrical storm (ES) is defined as a condition in which ventricular tachycardia (VT) or ventricular fibrillation (VF) episodes requiring electrical shock or implantable cardioverter-defibrillator (ICD) shocks occur ≥3 times within 24 h. It is a life-threatening condition, and treatment options include antiarrhythmic drugs, sedation, circulatory support, and catheter ablation. Sedation is conventionally performed for repeated electrical shocks; however, evidence for its effectiveness in ES suppression remains limited. This scoping review aimed to assess whether the use of sedatives is beneficial for ES suppression.

Methods and Results

This scoping review followed the PRISMA extension for scoping reviews (PRISMA-ScR) guidelines. Three online databases were searched to identify studies published from the inception of each database until September 18, 2024. To date, no randomized or quasi-randomized controlled trials or observational analytical studies have met the inclusion criteria for the use of sedation in patients with ES.

Conclusions

This scoping review underscores the need for high-quality studies to enhance the level of evidence and bridge knowledge gaps, ultimately aiming to shift the care paradigm for patients with ES.

Central Figure.

Electrical storm (ES) is defined as a condition in which ventricular tachycardia (VT) or ventricular fibrillation (VF) episodes requiring electrical shock or implantable cardioverter-defibrillator (ICD) shocks occur ≥3 times within 24 h. It is a life-threatening condition, and treatment options include antiarrhythmic drugs, sedation, circulatory support, and catheter ablation. VT and VF are the principal causes of sudden cardiac death and account for up to 80% of these events, particularly in patients with structural heart disease and impaired left ventricular function.¹ Despite advancements in implantable defibrillator therapy, the development of ES, especially in the form of repetitive VT/VF episodes, is strongly associated with increased mortality. In a multicenter registry, patients who experienced multiple ESs had a 3.39-fold higher mortality rate than those without.²

Furthermore, ES can develop even in patients treated with optimal antiarrhythmic regimens, including class III agents, such as amiodarone and nifekalant. In such refractory cases, intravenous β-blockers, such as landiolol, and deep sedation have been used as rescue strategies.^1,3 These episodes are not uncommon during the acute phase of myocardial infarction, with an estimated incidence of 5–8%, often requiring mechanical circulatory support such as extracorporeal membrane oxygenation.^4,5

Approximately 10–20% of patients with ICDs experience ES, often leading to a vicious cycle of frequent shocks, pain, psychological trauma, and progressive cardiac dysfunction.^2,4 According to the 2022 European Society of Cardiology guidelines,⁶ the management of these patients should involve a multidisciplinary team including electrophysiologists, intensivists, and anesthesiologists. However, this is not always feasible at all centers.

Retrospective clinical reports have described the use of propofol-based deep sedation in emergency settings, showing partial or complete suppression of VT/VF in patients unresponsive to antiarrhythmic drugs.⁷ The 2024 expert consensus also highlights sedation as a temporary but potentially lifesaving measure when arrhythmias are driven by adrenergic mechanisms.⁸ Although sedation is commonly used in the management of recurrent electrical shocks, evidence supporting its efficacy in suppressing ES remains scarce. Although several guidelines and expert consensus documents endorse the use of sedation for VF, detailed investigations or strong evidence supporting this recommendation are currently lacking. Therefore, we conducted a scoping review to explore the efficacy of sedation in the management of ES. This review was also performed to assess whether existing evidence supports the need for a systematic review in this context.

Methods

This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines.⁹

Identification of the Research Question

The number of studies addressing whether sedatives should be considered an adjunctive measure for arrhythmia suppression in patients with VT or VF storms was examined, and the interventions and outcomes reported in each study were analyzed.

Extraction of Relevant Studies

PubMed, the Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science and Igaku Chuo Zasshi were searched until September 18, 2024. The initial screening was performed using PubMed to identify the relevant literature and extract key words. Librarians from the JRC guidelines committee were requested to create a search strategy that was applied to each database. Details of the search strategy are provided in the Supplementary Appendix. Additionally, any potentially relevant literature not captured in the database searches was manually screened and included, where appropriate.

Study Selection

Eligibility and Selection Criteria Randomized and quasi-randomized controlled trials, as well as observational analytic studies (cohort studies, case-control studies, and cross-sectional studies), were included based on the following criteria: studies in adults (age ≥18 years) with ES, studies in which outcomes were reported as all-cause mortality, studies with cardiac death, studies with recurrence of VT or VF, and studies in which the number of defibrillation shocks was reported. All studies were published in English. After extracting relevant studies, duplicate records were removed using Rayyan software.

Primary Screening Three authors (T. Kitai, Y. Hosaka, T. Kawaji) independently reviewed all titles and abstracts to identify eligible studies. Case reports, case series, reviews, guidelines, animal studies, and studies that did not report original human clinical data related to the primary review question were excluded.

Secondary Screening The same 3 reviewers independently reviewed the full texts of potentially eligible studies to determine whether they met the inclusion and exclusion criteria. Disagreements were resolved through discussion.

Results

In total, 1,711 articles were screened based on their titles and abstracts, and 442 articles were excluded, including those clearly unrelated to ES. Of the remaining articles, 2 were deemed eligible for a full-text review; however, none met the predefined inclusion criteria for randomized or observational analytical studies. Therefore, a meta-analysis could not be performed (Figure).

Figure.

Flowchart of study selection for this review. A total of 1,711 records were identified through database searches (PubMed, CENTRAL, Web of Science, and Ichushi-Web). After removing duplicates, 1,269 records remained. Two full-text articles were assessed for eligibility; however, none met the inclusion criteria. Both the studies were excluded because they were retrospective in nature. None of the studies were included in the final review. Note: Two retrospective studies were considered for narrative purposes but were excluded from the formal review owing to their study design (non-analytic).

Nonetheless, 2 retrospective studies that provided preliminary insights into the potential role of deep sedation in ES management were identified (Table).

Table.

Summary of Retrospective Studies on Deep Sedation in ES

Study	Study design	Sample size (n)	Intervention	ES suppression	In-hospital mortality	Follow-up outcome
Martins et al.10	Multicenter retrospective	116	Deep sedation	47% (55/116)	23.6% (13/55) in responders vs. 52.4% (32/61) in non-responders; 55% lower risk (subhazard ratio 0.45 [95% CI 0.22–0.93]; P=0.03)	Not reported
Bundgaard et al.11	Single-center retrospective	15	Deep sedation	93% (14/15)	6.7% (1/15)	87% (13/15) alive after 3.7-year follow up

This table summarizes the key findings of retrospective studies that evaluated the effects of deep sedation on ES suppression, in-hospital mortality, and follow-up outcomes. CI, confidence interval; ES, electrical storm.

Martins et al. conducted a multicenter retrospective study involving 116 patients and reported an acute response rate of approximately 50% within 15 min of initiating deep sedation. An acute response was associated with a 55% reduction in in-hospital mortality, suggesting the possible prognostic benefit of an early response to deep sedation.¹⁰

Similarly, Bundgaard et al. described the outcomes of 15 patients with refractory VT/VF who underwent propofol-based deep sedation.¹¹ In this cohort, 93% of patients experienced complete or partial suppression of ventricular arrhythmias. The survival rate to hospital discharge was 87%, and continued clinical benefits were noted during follow up. These findings indicate the feasibility and possible efficacy of deep sedation as a bridge to definitive therapies, such as catheter ablation, surgical sympathetic denervation, and revascularization.¹¹

Discussion

Deep sedation has traditionally been considered a supportive measure for patients experiencing ES, primarily aimed at alleviating psychological distress and mitigating autonomic hyperactivation caused by recurrent defibrillator shocks. However, emerging evidence suggests that its role may extend beyond symptomatic relief. Retrospective studies have indicated that sedative agents, particularly propofol, may modulate the autonomic tone and acutely suppress ventricular arrhythmias, thereby serving as therapeutic bridges until definitive treatment becomes feasible.

Furthermore, deep sedation may provide clinical value in scenarios where catheter ablation is delayed or not immediately feasible, particularly in resource-limited or critically ill settings. These considerations underscore the need for structured context-sensitive protocols that incorporate deep sedation as a deliberate component of acute ES management. Notably, the implementation of deep sedation may facilitate interdisciplinary collaboration among cardiologists, intensivists, and anesthesiologists, thereby promoting comprehensive care in high-acuity environments.

This evolving perspective necessitates the reframing of deep sedation, from a passive or palliative intervention to a potentially active therapeutic modality for suppressing adrenergically driven arrhythmias. As the field anticipates results from ongoing prospective studies, such as the SEDATE (Study Evaluating Dexmedetomidine in the Acute Treatment of Electrical Storm) trial, renewed attention must be given to the development of standardized sedation protocols that address patient selection, timing, and safety considerations. This conceptual shift provides a foundation for a more nuanced understanding of the therapeutic potential of deep sedation in arrhythmia care, which is further examined in a subsequent section.

Strengths

This scoping review offers a comprehensive and timely synthesis of the current literature on the role of deep sedation in the management of ES, a clinically significant yet underexplored area in arrhythmia care. A particular strength of this review lies in its identification of deep sedation, not merely for symptomatic relief, but as a potential bridging strategy to definitive therapies in patients with hemodynamic instability or refractory ventricular arrhythmias. In accordance with the PRISMA-ScR framework, this review used a rigorous and systematic search strategy across multiple databases supported by expert consensus guidance, thereby enhancing the credibility and scope of the findings.

By mapping the existing evidence, this review supports the hypothesis that deep sedation may play a proactive role in modulating autonomic tone and stabilizing arrhythmias during acute ES episodes. Furthermore, it highlights the urgent need for prospective clinical trials and guideline development to formulate sedation strategies in this setting.

Study Limitations

Several limitations should be acknowledged. First, because of the inherent nature of a scoping review, we did not assess the specific physiological mechanisms through which sedative agents influence arrhythmogenic substrates, an area that warrants further investigation in future mechanistic studies. Second, while the literature search was comprehensive, the exclusion of non-English language publications and gray literature may have introduced a potential language or publication bias. Last, the generalizability of the findings is limited by the predominance of small, retrospective, and heterogeneous studies, which restricts the ability to draw definitive clinical recommendations.

Despite these limitations, this review provides a valuable foundation for hypothesis generation and serves as a directional platform for future research aimed at optimizing sedation protocols for the acute management of ESs.

Conclusions

At present there is insufficient evidence to support routine use of sedative drugs for ES suppression. Although existing studies suggest that deep sedation may be effective in select cases, further randomized controlled trials are necessary to confirm its efficacy.

Disclosures

T.M. is a member of Circulation Reports’ Editorial Team.

IRB Information

Not applicable. All procedures in this study were conducted in accordance with the ethical standards of the responsible institutional and/or regional committee on human experimentation and with the 1964 Declaration of Helsinki and its later amendments.

Supplementary Files

Supplementary File 1

Supplementary Appendix.

Funding Statement

Sources of Funding: This work was supported by the Japan Resuscitation Council, Japanese Circulation Society, and JSPS KAKENHI (grant no. JP23K08454).

Data Availability

All data generated or analyzed are included in this article.