Feature | Defibrillator Monitors | July 10, 2018 | Michael J. Mirro, M.D.

Diving Deeper Into the Results of the VEST Trial Using Wearable Defibrillators

Getting the whole story from clinical trials aids evidenced-based medicine

The Zoll LifeVest wearable defibrillator was the subject of the VEST Trial

The Zoll LifeVest wearable defibrillator system was evaluated in the late-breaking VEST Trial presented at ACC 2018 earlier this year.

Following the Vest Prevention of Early Sudden Death Trial (VEST) presentation at the 2018 American College of Cardiology (ACC) Scientific Session, there has been much debate about the results of this trial and what it tells us about the utility of the wearable cardioverter defibrillator (WCD) in our treatment of patients at risk of experiencing sudden cardiac death (SCD).[1]

The VEST Trial is a randomized control trial studying patients with EF ≤35 percent after myocardial infarction with guideline directed medical therapy. Patients were randomized to receive the WCD and optimal medical therapy and were compared to a group receiving only optimal medical therapy. They were followed for 90 days and the results were analyzed and presented as intention to treat.

As we observed, the trial demonstrated a reduction in the primary endpoint of Sudden Death (SD) mortality, but this reduction did not reach the prespecified threshold for statistical significance. As a result, some are dismissing the results of this trial as it missed the primary endpoint.  However, the trial also demonstrated a significant reduction in the prespecified secondary endpoint of total mortality (1.8 percent ARR; 36 percent RRR) in just 90 days (the follow up period of the trial).

For some, the reaction to clinical trials tends to be very black and white. Sometimes these assessments are based on a single piece of data or a “purist” view of statistics. Often, there is more to the story, as is the case with the VEST trial, and we owe it to our patients, as members of the medical profession, to take a deeper dive below the surface and more thoroughly investigate this story to keep their health and well-being the first and foremost consideration in our care of them.

Mechanistically, the sudden death and total mortality outcomes do not make sense, or so we have been told, so let's examine beneath the surface.  First, the WCD did reduce SD during the 90-day study period. This did not reach statistical significance for purposes of a clinical trial definition, but there is a reduction (2.4 percent in the control versus 1.6 percent in the WCD arm). There were also 14 patients who received an appropriate treatment from the WCD and survived to 90 days. This represents over half of the 1.7 percent absolute risk reduction between the two groups. Additionally, there were 70 patients that used the response buttons on the WCD to abort a shock. This early warning of a potentially life-threatening medical condition may have saved lives – just not by shocking a lethal arrhythmia. This is possibly a further “dilution” of the primary outcome. But does this mean that these patients did not benefit from the WCD?


Value of the VEST Trial

The reason we do clinical trials is to learn more about therapies and, ultimately, to understand how we can improve patient care. To dismiss a trial based on the fact that an outcome was not statistically significant disregards the primary purpose of clinical trials, and that is to learn more than we previously knew, and to use that knowledge to improve the care of our patients. In that regard, the VEST trial is a success.  If we as clinicians choose not to examine the totality of the data from a clinical trial, we are choosing not to learn everything we can to advance the care of our patients.

In 2017, the World Medical Association Declaration of Geneva was once again updated.[2] One of the first tenets of this modern update to the Hippocratic Oath states that “as a member of the medical profession, the health and well-being of my patient will be my first consideration.” In that spirit, we should take a closer look at the VEST trial data as there are several takeaways that are worth considering.  

VEST confirmed that low-EF, post-MI patients are a difficult population to treat as evidenced by the fact that about 1 in 20 patients (4.9 percent) in the control arm died in the first 90 days despite being on GDMT, and approximately half of this was due to SD. This is a population for which we can improve outcomes. For the well-being of our patients, we can not ignore the outcome of a 36 percent improvement in total mortality over a 90 day period.

Shortly after the ACC, investigators also shared preliminary on-treatment analysis data showing that when worn, the WCD significantly reduced both sudden cardiac death and total mortality. And, when patients chose to wear the WCD, they wore it well — from 22.4 hour to 21 hours per day over the 90 day follow-up period.

When looking at the full story of VEST, I have learned that by using the WCD, we can save lives. I also learned that the world of randomized clinical trials and that of real-world clinical practice are not the same. Patients are only as committed to therapies and care plans as we are.


Wearable Defibrillators and Shared Decision Making

The 2017 American Heart Association (AHA)/American College of Cardiology (ACC)/Heart Rhythm Society (HRS) Guidelines for Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death list shared-decision making as a Class I recommendation, stating “clinicians should adopt a shared decision-making approach in which treatment decisions are based not only on the best available evidence but also on the patients’ health goals, preferences, and values.”[3]

Making the patient part of the discussion and decision is critical to the patient’s adherence and acceptance of therapy. The early data from VEST suggests that there’s a major opportunity to improve outcomes if we can encourage patients to be more faithful to their therapies. In the VEST intention to treat results, the WCD significantly reduced mortality indicating the benefit could be much greater if more patients adhere.  Patients need to understand their risk and understand the potential of the WCD to improve their outcome. It is ultimately up to the patient, and the WCD may not be right for everyone, but every patient deserves the opportunity to make that choice.


Mike Mirro, M.D.Editor's Note: Michael J. Mirro, M.D., FHRS, FACC, FACP, FAHA, is chief academic research officer at Parkview Health and the director of the Mirro Center for Research and Innovation at Parkview, in Ft. Wayne, Ind. He founded the electrophysiology program at Parkview Health.





1. Olgin J, Pletcher M, Vittinghoff E, et al. Vest Prevention of Early Sudden Death Trial: Efficacy of a wearable cardioverter-defibrillator after myocardial infarction. Presented as Late Breaking Clinical Trial at the 2018 American College of Cardiology Annual Scientific Sessions, March 10, 2018.

2. Parsa-Parsi RW. The Revised Declaration of Geneva A Modern-Day Physician’s Pledge. JAMA.2017;318(20):1971–1972. doi:10.1001/jama.2017.16230

3. Al-Khatib SM, Stevenson WG, Ackerman MJ, Bryant WJ, Callans DJ, Curtis AB, Deal BJ, Dickfeld T, Field ME, Fonarow GC, Gillis AM, Hlatky MA, Granger CB, Hammill SC, Joglar JA, Kay GN, Matlock DD, Myerburg RJ, Page RL, 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death, Journal of the American College of Cardiology (2017), doi: 10.1016/j.jacc.2017.10.054.

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