In patients with ischemic cardiomyopathy (LVEF ≤35%) due to acute myocardial infarction, do wearable cardioverter-defibrillators (WCDs) reduce arrhythmic death compared to medical therapy?
In patients with ischemic cardiomyopathy (LVEF ≤ 35%) due to acute myocardial infarction, use of a wearable cardioverter-defibrillator (WCD) did not reduce arrhythmic death compared to medical therapy alone. In an as-treated analysis, WCD wear time was associated with a 60% reduction in arrhythmic death, although as-treated analyses are subject to bias.
It is well-known that patients with acute ischemic cardiomyopathy resulting in LVEF ≤ 35% are at relatively high risk for arrhythmic death in the immediate post-MI period. However, studies investigating the efficacy of implantable cardioverter-defibrillators (ICD) shortly after an MI (DINAMIT) or after multivessel revascularization (CABG-PATCH) have failed to demonstrate a benefit.
The 2018 Vest Prevention of Early Sudden Death Trial (VEST) randomized 2302 patients with acute ischemic cardiomyopathy due to MI resulting in LVEF ≤ 35% to WCD versus medical therapy and assessed for a primary outcome of arrhythmic death. At mean 84 days, there was no difference in arrhythmic death between the WCD and the medical therapy groups. Interestingly, there was a 1.8% absolute reduction in all-cause death, although this was driven substantially by non-arrhythmic death; since a reduction in non-arrhythmic death due to WCD is implausible and all-cause death was a secondary outcome not adjusted for multiple comparisons, this is most likely a chance finding. In an as-treated analysis, actual WCD wear time was associated with a relative 60% reduction in arrhythmic death as well as a 1.41 per 100 person-month reduction in all-cause death, although as-treated analyses are subject to bias and should be interpreted with caution. For example, it is possible that patients at lower risk for arrhythmia tend to contribute a greater proportion of wear time among patients randomized to WCD, leading to a perceived decrease in arrhythmic death in the absence of an actual benefit to WCD.
In summary, the results of VEST suggest that routine use of WCDs in patients with ischemic cardiomyopathy does not improve arrhythmic death. Although as-treated analyses should be interpreted with caution due to potential for bias, the signals for improved arrhythmic and all-cause death with WCD wear time does suggest that the devices may be effective at aborting sudden cardiac death when actually worn (i.e., very motivated patients). Ultimately, WCD use is likely to decrease significantly in clinical practice as a result of these findings.
As of October 2018, no guidelines have been published that reflect the results of this trial.
- Multicenter, randomized, open-label, controlled trial
- WCD (N=1524)
- Medical therapy (N=778)
- Setting: 76 sites in US, Poland, Germany, and Hungary
- Enrollment: July 2008 - April 2017
- Mean follow-up: 84 days
- Analysis: Intention-to-treat
- Primary Outcome: Arrhythmic death
- Age ≥ 18 years
- Hospitalized for or within 7 days of discharge from hospitalization for acute MI
- LVEF ≤ 35% determined at:
- If no PCI, ≥ 8 hours
- If acute PCI, ≥ 8 hours
- If CABG, ≥ 48 hours
- Existing ICD or indication for ICD
- Existing unipolar pacemaker/leads
- Chronic renal failure requiring hemodialysis after hospital discharge
- Chest circumference too small/large for WCD
- Participants discharged to a skilled nursing facility with anticipated stay > 7 days
- Inability to consent
- Any condition/circumstance that makes the patient unsuitable for the study
From the control group.
- Demographics: Age 61.4 years, male 74.7%, white 84.7%
- Comorbidities: BMI 28.4, smoker 35.5%, DM 31.7%, HTN 64.6%, previous MI 24.9%, previous CABG 9.0%, previous PCI 26.0%, CHF 18.9%, maximum creatinine 1.1
- CHF: NYHA I 42.1%, NYHA II 36.9%, NYHA III 15.0%, NYHA IV 2.3%, LVEF 28.2%
- Treatment: PCI during index 84.1%, CABG during index 1.5%, lytic during index 9.2%, IABP 12.0%
- Complications of MI: Cardiac arrest or VF 9.1%, pulmonary edema requiring intubation 11.4%, AF 11.8%
- Medications: aspirin 87.1%, other antiplatelet 87.4%, statin 89.5%, beta blocker 92.5%, ACE/ARB 85.7%, MRA 44.1%, other diuretic 49.5%, amiodarone 7.1%, other antiarrhythmic 0.5%, digoxin 5.7%
- Patients randomized 2:1 to wearable cardioverter defibrillator (WCD) or medical therapy alone
- WCD (N=1524)
- Medical therapy (N=778)
- Prior to enrollment, participants were fitted with the Zoll LifeVest WCD, trained in its use, and instructed to wear the device continuously for 3 months (except while bathing)
- Sites were alerted if the device was used for less than 15 hours in a 24 hour period
- Arrhythmias detected by the device were not reported to treating physicians or the trial sites unless a shock was delivered or cardiac arrest occurred
- Crossovers from medical therapy to device group were not permitted
- Early ICD implantation (within 3 months) was not allowed unless for guideline-based secondary prevention
- Participants were followed at 1 month with a telephone call and at 3 months with an in-person visit
- Cause of death was adjudicated by an independent panel of experts unaware of group assignment
- Participants with an indeterminate cause of death were assumed not to have had arrhythmic death but were counted in the outcome of death from any cause
- All participants with missing vital status were assumed to be alive
Comparisons are WCD versus medical therapy
- Arrhythmic death
- 25 (1.6%) vs. 19 (2.4%); HR 0.67, 95% CI (0.37-1.21); p = 0.18
- Non-arrhythmic death
- 21 (1.4%) vs. 17 (2.2%); HR 0.63, 95% CI (0.33-1.19); p = 0.15
- Indeterminate death
- 2 (0.1%) vs. 2 (0.3%); HR 0.51, 95% CI (0.04-7.05); p = 0.83
- Any death
- 48 (3.1%) vs. 38 (4.9%); HR 0.64, 95% CI (0.43-0.98); p = 0.04
- Any rehospitalization
- 475 (31.2%) vs. 253 (32.5%); HR 0.96, 95% CI (0.85-1.09); p = 0.51
- Open-label design allows for bias in the assessment of outcomes. Verification of outcomes by an independent adjudication committee blinded to treatment assignment somewhat mitigates this bias.
- Relatively short duration of follow-up may limit power to detect a smaller benefit on arrhythmic death with WCD (study powered to detect a 58% reduction in arrhythmic death).
- Particularly given as-treated analyses suggesting a benefit to WCD when worn, it is possible that an as-yet-unidentified subgroup of patients more likely to adhere to WCD may derive benefit. This requires further study.
- Study supported by Zoll, who had no role in the study design, selection or supervision of trial centers, analysis or interpretation of the data, preparation of the manuscript, or decision to submit the manuscript for publication. Zoll did participate in site monitoring.
- Authors with multiple ties to industry, including the study sponsor.