Wearable cardioverter defibrillator for preventing sudden cardiac death in patients at risk: An updated systematic review of comparative effectiveness and safety

Abstract

Objectives: To synthesise the available evidence of wearable cardioverter defibrillator (WCD) therapy as an add-on measure to optimal medical therapy (OMT) or as a replacement of hospital stay.

Methods: An update systematic review (SR) of comparative effectiveness and safety of WCD therapy was conducted. We included randomised controlled trials (RCT), prospective comparative studies and prospective uncontrolled studies with at least 100 patients. A narrative synthesis of the evidence was conducted.

Results: One RCT (n = 2348) and further eleven observational studies (n = 5345) fulfilled our inclusion criteria. In the only available RCT, the use of the WCD was not statistically associated with a clinical benefit on arrhythmic mortality in post-myocardial infarction (MI) patients with an ejection fraction of ≤35%. The compliance with WCD therapy was low in the RCT and high in observational studies, with ten observational studies reporting on a daily wear time between 20 and 23.5 h. The range of percentage of patients receiving at least one appropriate shock was 1-4.8% and the rate of first shock success was reported to be 100% in three studies. Serious adverse events (SAEs) such as inappropriate shocks occurred rarely, with between 0% and 2% of patients being inappropriately shocked within ten observational studies. In one of the observational studies, two patients (2%) were allergic to nickel developing skin rash and false alarms occurred in 58 patients (57%) in this study. Another registry study (n = 448) reported milder AEs, such as dermatitis and pressure marks, occurring in 0.9% and 0.2% of enrolled patients, respectively.

Conclusion: The only available RCT failed to show superiority of add-on use of WCD in post MI patients. Observational evidence shows that the compliance with WCD is good, but the evidence is afflicted with selection bias and the inclusion of diverse mixed patient populations diluting the ability to draw indication-specific conclusions on the utility of the device. More comparative data is needed to justify continuing or expanding use of WCD therapy.

Keywords: (cardioverter-) defibrillator (external; Countershock; Sudden cardiac arrest; Ventricular fibrillation; Ventricular tachycardia; Wearable).

Fig. 1

PRISMA flow chart: study selection.

Fig. 2

Risk of bias of the randomised controlled trial Full risk of bias assessment can be found elsewhere [13]. Abbreviations: D – domain.

Fig. 3

Risk of bias of non-randomised controlled trials Full risk of bias assessment can be found elsewhere [13]. Abbreviation: D - domain.

Fig. 4

Risk of bias of uncontrolled observational studies. Abbreviations: D – domain; Q – question. D1: Study objective. Q1: Was the hypothesis/aim/objective of the study clearly stated?. D2: Study design. Q2: Was the study conducted prospectively?. Q3: Were the cases collected in more than one centre?. Q4: Were patients recruited consecutively?. D3: Study population. Q5: Were the characteristics of the patients included in the study described?. Q6: Were the eligibility criteria (i.e. inclusion and exclusion criteria) for entry into the study clearly stated?. Q7: Did patients enter the study at a similar point in the disease?. D4: Intervention and cointervention. Q8: Was the intervention of interest clearly described?. Q9: Were additional interventions (co- interventions) clearly described?. D5: Outcome measures. Q10: Were relevant outcome measures established a priori?. Q11: Were outcome assessors blinded to the intervention that patients received?. Q12: Were the relevant outcomes measured using appropriate objective/subjective methods?. Q13: Were the relevant outcome measures made before and after the intervention?. D6: Statistical Analysis. Q14: Were the statistical tests used to assess the relevant outcomes appropriate?. D7: Results and Conclusions. Q15: Was follow-up long enough for important events and outcomes to occur?. Q16: Were losses to follow-up reported?. Q17: Did the study provide estimates of random variability in the data analysis of relevant outcomes?. Q18: Were the adverse events reported?. Q19: Were the conclusions of the study supported by results?. D8: Competing interests and sources of support. Q20: Were both competing interests and sources of support for the study reported?