Dual Sequential Defibrillation vs standard therapy for patients with refractory ventricular fibrillation
Date First Published:
January 5, 2026
Last Updated:
January 5, 2026
Report by:
Dr Gregory Smith, ST3 Emergency Medicine (Liverpool University Teaching Hospitals)
Search checked by:
Rob Evans, Senior HEMS Paramedic Team Leader, North West Air Ambulance
Three-Part Question:
In [patients with refractory ventricular fibrillation] is [dual sequential defibrillation better than standard defibrillation strategies] at [improving survival]?
Clinical Scenario:
A 55-year-old patient in cardiac arrest has received 3 unsynchronised shocks but remains in ventricular fibrillation. You must decide whether to continue standard defibrillation at the same energy or attempt dual sequential defibrillation if the patient remains in VF at the next rhythm check.
Search Strategy:
A focused literature search was conducted using PubMed, EMBASE and Cochrane to identify relevant literature comparing dual sequential defibrillation with standard defibrillation strategies for patients with refractory ventricular fibrillation.
Search Details:
Search terms: ("refractory" AND "VF" OR "Ventricular fibrillation") AND ("treatment" OR "therapy" OR "defibrillation" OR "DSD" OR "dual sequential defibrillation" OR "double sequential defibrillation"). Limited to adults and English language.
Outcome:
8 studies were included - These included 1 RCT, 2 secondary analyses of this RCT, 2 systematic reviews, 2 retrospective cohort studies, and 1 matched case-control study.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| Defibrillation Strategies for Refractory Ventricular Fibrillation (DOSEVF) Cheskes S, Verbeek PR, Drennan IR, et al. 2022 Canada | Adults with OOHCA in refractory VF or VT of presumed cardiac origin – defined by VF after 3 standard shocks | Multicentre RCT | Survival to hospital discharge | Higher survival to hospital discharge in patients receiving DSD and VC defibrillation vs standard therapy | Underpowered due to stopping recruitment early, increasing the risk of type 1 error. Low number of outcome events Baseline differences between intervention and control groups No long-term follow-up after discharge The benefit seen in the VC group had a high fragility index. |
| Defibrillation and refractory ventricular fibrillation Verkaik BJ, Walker RG, Taylor TG et al. 2025 The Netherlands | Patients with medical OOHCA and VF as initial rhythm requiring at least 4 consecutive standard shocks | Observational cohort study | Rate of recurrence of VF on rhythm strip | Of 4993 cases of OOHCA, 95% had recurrent VF. Altogether, VF was terminated in 77% of the first three shocks combined. The first three shocks terminated VF at least once in 95%, at least twice in 81%, and with all three shocks in 55% of patients. | Observational study Early time to bystander CPR and first shock may limit validity to other systems. |
| The impact of alternate defibrillation strategies on time in ventricular fibrillation Cheskes S, Drennan IR, Turner L et al. 2025 Canada | Patients enrolled in the DOSEVF RCT | Secondary analysis of RCT trial | Duration of VF | 1842 shocks analysed: 429 standard, 218 VC, 187 DSED. | Observational study As per DOSEVF |
| Median VF time was significantly shorter for DSED and VC compared to standard shocks. | |||||
| Proportion of shocks leading to ROSC and survival to hospital discharge was higher for DSED and VC than for standard shocks. | |||||
| Beyond Standard Shocks: A Critical Review of Alternative Defibrillation Strategies in Refractory Ventricular Fibrillation Perna B, Guarino M, De Fazio R et al. 2025 Italy | Adult patients with refractory VF | Systematic review | Survival to hospital discharge | There is only 1 RCT (DOSEVF) that has shown both DSED and VCD improved survival to hospital discharge, with DSED also improving ROSC, VF termination, and neurological outcomes. Subsequent reviews have questioned consistency, given earlier weak studies and variability in shock timing, energy, and protocols. | Doesn’t state number of studies and patients included. Included low quality retrospective evidence, with heterogeneity in methods and practice. |
| Rate of ROSC | |||||
| Survival with good neurological function | |||||
| Defibrillation strategies for patients with refractory ventricular fibrillation: A systematic review and meta-analysis Jinzhou Yu, Yanwu Yu, Huoyan Liang et al. 2024 USA | Adult patients with refractory VF receiving dual sequential or simultaneous defibrillation | Systematic review with meta-analysis Included 6 trials comprising 1306 patients. 1 RCT and 5 observational cohort studies. 1 RCT and 2 observational studies used Dual sequential defibrillation, with the other 3 observational studies utilising dual simultaneous defibrillation. |
Rate of survival to hospital discharge | DSD has shown benefit in the DOSEVF RCT, but pooled results of the observational studies showed no benefit. Dual simultaneous defibrillation was linked with lower rates of ROSC than standard defibrillation. | Included low quality retrospective evidence, with heterogeneity in methods and practice, and differences in baseline characteristics between the control and intervention groups. |
| Incidence of ROSC | |||||
| Termination of VF | |||||
| Survival to hospital admission | |||||
| Survival with good neurological outcome | |||||
| Effectiveness of Prehospital Dual Sequential Defibrillation for Refractory Ventricular Fibrillation and Ventricular Tachycardia Cardiac Arrest Beck LR, Ostermayer DG, Ponce JN et al. 2019 USA | Adults with OOHCA requiring at least 3 standard defibrillation attempts | Retrospective observational cohort analysis in the use of dual simultaneous defibrillation vs standard shocks. | Pre-hospital ROSC | Lower rate of ROSC in DSD group. | Small number in intervention group Criteria for DSD not stated |
| Survival to hospital | No difference in survival to admission, at 72h or at discharge | ||||
| 72h survival | |||||
| Survival to discharge | |||||
| Association of coronary angiography with ST-elevation and no ST-elevation in patients with refractory ventricular fibrillation - A substudy of the DOuble SEquential External Defibrillation for Refractory Ventricular Fibrillation (DOSE-VF randomized control trial) Deb S, Drennan IR, Turner L et al. 2024 Canada | Patients enrolled into the DOSEVF RCT | Secondary analysis of DOSEVF | Proportion of patients in DOSEVF who received DSD with STE and NSTE that underwent invasive coronary angiography | 151 patients, 49% with STE and 51% with NO-STE. | Observational study As per DOSEVF |
| The proportion of angiography was higher in the STE cohort than NO-STE (87.8% vs 44.2%, p < 0.001); similarly the proportion of PCI was also higher (75.7% vs 9.1%, p < 0.001). Survival to discharge was similar between STE and NO-STE (63.5% vs 51.9%, p = 0.15). Use of angiography/PCI did not differ between defibrillation strategies. | |||||
| Prehospital Double Sequential Defibrillation: A Matched Case–Control Study Mapp JG, Hans AJ, Darrington AM et al. 2019 Canada | Pre-hospital patients with refractory Vf/pVT, defined as the administration of at least three conventional 200-J defibrillations without conversion to a non-shockable rhythm | Matched case–control study | Survival to hospital admission | Survival to admission occurred in 48% of DSD cases and 50.5% of conventional therapy patients. Prehospital ROSC occurred in 20% DSD and 40.8% conventional therapy; Survival to hospital discharge – 16% in DSD and 23.3% in conventional group. | Matched case-control design that is prone to bias, although potentially useful to generate hypothesis; small sample size; survival to hospital admission doesn’t necessarily translate to long-term survival/good neurological outcome; differences in baseline characteristics between groups – in initial treatment by bystanders and EMS. |
| Prehospital return of spontaneous circulation (ROSC) | |||||
| Survival to hospital discharge | |||||
| Neurologically intact survival to hospital discharge |
Author Commentary:
The existing literature on alternative defibrillation strategies is marked by significant heterogeneity in study design and DSD protocols, with wide variation in shock timing and when escalation was introduced in the resuscitation algorithm. The DOSE-VF trial remains the only randomised controlled study in this field and demonstrated promising outcomes with both DSD and VC defibrillation. Secondary analyses also showed that DSD shortens VF duration and improves survival to hospital discharge independently of in-hospital interventions. There is also evidence that shorter shock intervals (<75 ms) may enhance outcomes, though no trials have directly compared simultaneous versus sequential shock delivery.
Despite the significant results, DOSE-VF was underpowered, and the findings contrast with most retrospective cohort studies, though these are of lower quality and prone to bias.
VC defibrillation may represent a more practical option, as it requires only a single defibrillator, but its survival benefit in DOSE-VF was weaker than that of DSD, with a high fragility index.
Ultimately, further high-quality research is needed to clarify the role of DSD and VC in refractory VF, particularly regarding their optimal timing, impact in recurrent versus refractory VF, and variation in outcomes by patient and event characteristics.
Despite the significant results, DOSE-VF was underpowered, and the findings contrast with most retrospective cohort studies, though these are of lower quality and prone to bias.
VC defibrillation may represent a more practical option, as it requires only a single defibrillator, but its survival benefit in DOSE-VF was weaker than that of DSD, with a high fragility index.
Ultimately, further high-quality research is needed to clarify the role of DSD and VC in refractory VF, particularly regarding their optimal timing, impact in recurrent versus refractory VF, and variation in outcomes by patient and event characteristics.
Bottom Line:
DSD and VC defibrillation show promise with evidence of improved outcomes compared to standard defibrillation. However, the overall evidence is weak, with variation in study protocol and results. More high-quality research is needed on this subject to inform practice and change guidelines on the management of refractory VF.
For this reason, updated 2025 Resus council guidelines do not recommend routine use of DSD in refractory VF due to the practical challenges and limited evidence for efficacy.
For this reason, updated 2025 Resus council guidelines do not recommend routine use of DSD in refractory VF due to the practical challenges and limited evidence for efficacy.
Level of Evidence:
Level 3: Small numbers of small studies or great heterogeneity or very different population
References:
- Cheskes S, Verbeek PR, Drennan IR, et al.. Defibrillation Strategies for Refractory Ventricular Fibrillation (DOSEVF)
- Verkaik BJ, Walker RG, Taylor TG et al.. Defibrillation and refractory ventricular fibrillation
- Cheskes S, Drennan IR, Turner L et al.. The impact of alternate defibrillation strategies on time in ventricular fibrillation
- Perna B, Guarino M, De Fazio R et al.. Beyond Standard Shocks: A Critical Review of Alternative Defibrillation Strategies in Refractory Ventricular Fibrillation
- Jinzhou Yu, Yanwu Yu, Huoyan Liang et al.. Defibrillation strategies for patients with refractory ventricular fibrillation: A systematic review and meta-analysis
- Beck LR, Ostermayer DG, Ponce JN et al.. Effectiveness of Prehospital Dual Sequential Defibrillation for Refractory Ventricular Fibrillation and Ventricular Tachycardia Cardiac Arrest
- Deb S, Drennan IR, Turner L et al.. Association of coronary angiography with ST-elevation and no ST-elevation in patients with refractory ventricular fibrillation - A substudy of the DOuble SEquential External Defibrillation for Refractory Ventricular Fibrillation (DOSE-VF randomized control trial)
- Mapp JG, Hans AJ, Darrington AM et al.. Prehospital Double Sequential Defibrillation: A Matched Case–Control Study