Wearable defibrillator is said to save lives, but patients and doctors question at what cost

Joy Victory is deputy managing editor of HealthNewsReview.org. She tweets at @thejoyvictory.

In the summer of 2015, while standing in her kitchen, Rachel Pezzani heard her 11-year-old daughter Natalie scream from another room.

Natalie Pezzani

Pezzani raced to her, scared that Natalie’s wearable “LifeVest” defibrillator was about to go off.

Natalie, still recovering from recent emergency heart surgery related to a birth defect, was wearing the device per hospital discharge orders, until she was strong enough to have a pacemaker surgically implanted. She also was on heart stabilizing medication–but if it failed, and she went into sudden cardiac arrest and fell unconscious–the LifeVest was supposed to deliver shocks that could potentially save her life.

Natalie was distraught, but the device was silent. It didn’t seem to be preparing itself to defibrillate. Natalie’s heart was OK, Pezzani realized. However, something else was wrong: Gel was oozing out of the defibrillator pads attached to Natalie’s skin. And beneath the gel, Natalie’s skin appeared scorched.

Pezzani, of Hillsboro, Mo., immediately reported the incident. Natalie’s healthcare providers were stumped, yet insistent that Natalie must wear a LifeVest. And ZOLL Medical Corporation, the device maker, could offer no explanation, Pezzani said, but they sent a new vest. That didn’t help: In all, Pezzani said, similar incidents happened six more times. On top of that, the device frequently issued warning alarms, terrifying the entire family and traumatizing her daughter. 

Several months later, exhausted, frustrated and without clear answers as to what was going on, Pezzani took her daughter to a pediatric heart surgeon Natalie had seen in the past, for a second opinion. “The first thing he said to me was ‘get it off her, just get rid of it,’” Pezzani said. “He said ‘Let me ask you a question: Has [the vest] ever gone off properly?’ And I said no, and he said ‘then the medicine must be doing its job.’”

It was an enormous relief. “This child has been through too much, especially to have her burned,” Pezzani said. “Enough is enough.”

But their saga wasn’t quite over yet. Natalie’s skin wounds meant her implantable pacemaker surgery had to be delayed.

“We had to let her heal. It took over two months for it to heal enough for him to get in there and place the pacemaker,” said Pezzani. She has hired a lawyer who may pursue legal action against ZOLL.

Numerous reports related to patient safety

Natalie’s experience is not unique. Adverse events connected to the ZOLL LifeVest appear common. However, finding out about these risks from healthcare providers isn’t easy, some patients and doctors report–and it’s only made harder by the reality that nearly all news stories and patient information websites gloss over the risks. Medical devices are loosely regulated by the FDA and don’t have to meet the same safety standards as drugs.

The LifeVest was approved by the FDA in 2001, and has been prescribed more than 35,000 times, according to ZOLL, which is based in Pittsburgh and part of the Asahi Kasei Group Company. It is the only wearable defibrillator on the market. In 2015, the LifeVest also was approved for children, though the device is not modified to fit them. 

Just how risky is the LifeVest? It’s hard to know for sure. In the FDA’s “Manufacturer and User Facility Device Experience” database (known as MAUDE), there are numerous reports of deaths, injuries, and device malfunctions associated with the device. But it’s not a comprehensive list, since only ZOLL is federally required to submit reports, and there is little oversight to make sure they do. Doctors and patients can submit reports voluntarily.

Skin inflammation is a common complaint. So too are “inappropriate” shocks delivered to conscious patients. In one extreme example from the database, a woman experienced 39 shocks:

“A [U.S.] distributor contacted Zoll to report that a patient experienced an inappropriate defibrillation event consisting of 39 shocks while in the hospital. The patient’s sister reported that the patient is forgetful and likely did not press the response buttons. Review of the download data indicates that the response buttons were not pressed during the event. The patient remained in the hospital following the event and passed away two weeks later. The cause of the patient’s death is unknown.”

And two weeks ago, another problem surfaced, when the FDA issued a safety alert about the device sometimes sending out a vague error alarm. In at least one case, it was linked to a patient death. ZOLL has issued a recall for vests that display the specific error.

When asked for comment about these problems, a public relations contact at ZOLL declined to answer questions, and sent this statement:

“On any given day, tens of thousands of people around the world are protected from SCD by the LifeVest Wearable Defibrillator. LifeVest is used for a wide range of patient conditions or situations, including following a myocardial infarction, before or after coronary revascularization, and for those with cardiomyopathy or congestive heart failure that places them at particular risk. LifeVest gives physicians time to optimize medical therapy and assess a patient’s long-term risk for sudden death.”

Patients and doctors say there’s little chance of informed consent

As ZOLL notes, this is a patient population at high risk of dying already. And for a host of reasons, it isn’t possible to say definitively whether the device contributed to the injuries and deaths reported in the MAUDE database.

That said, though, the LifeVest is a powerful device that can harm patients. Are patients getting informed of the risks?

Pezzani and several doctors we spoke to said no. They recounted scenarios in which patients were told they must wear the vest if they want to leave the hospital.

“ZOLL reps, they come to the hospital, there’s no choice,” Pezzani said. “I was not given a choice whether or not to use it. They would not allow her to go home. They have this rep coming in, and they don’t say ‘read through everything, take your time.’”

A similar patient story is recounted in a blog post by Kentucky cardiac electrophysiologist John Mandrola, MD, who has been openly critical of the vest.

And, Anthony Pearson, MD, a St. Louis-area cardiologist, recalled a patient of his who was being discharged from the hospital with atrial fibrillation and heart failure.

“The [nurses] are very pro LifeVest, they consider you a bad doctor if you don’t talk to your patient about it,” Pearson said in a phone interview. “They talked to my patient–I had never said anything to him–they told him he needed a LifeVest. From what he tells me, they basically told him he had to have it. And they told him ‘don’t worry about the insurance.’ The ZOLL people told him similar things, ‘don’t worry, it will be fine.’” Despite this, Pearson said the patient got in a protracted tug-of-war with his insurance company over a $13,000 bill, which ultimately he didn’t have to pay.

No informed choice, and then lopsided information online

Once home, and strapped into a powerful, roughly $3,000-a-month device they’re told to remove only rarely, patients who want to know more about their LifeVest will be hard-pressed to find balanced information in news reports online, or from patient advocacy organizations.

For this article, I read nearly a dozen news stories about the LifeVest, and only two mentioned any risks. This HealthDay News story was the most cautious of the bunch, illuminating several important risks–and the lack of proven benefit. And this U.S. News & World Report feature story on sudden cardiac arrest in children also included a sentence on risks of the vest.

For the most part, though, the news stories are akin to this Florida Today story, where a patient’s harrowing story is profiled and the LifeVest is framed as life-saving. Other examples include these stories from a Phoenix radio station, a Raleigh, N.C. CBS affiliate, and a Tennessee newspaperThis relatively in-depth patient story published in the Austin American-Statesman’s tech blog mentions the device is clunky–but not potentially harmful.

The same pattern exists for patient-focused content. Perhaps not surprisingly, ZOLL’s own patient page mentions no downsides. Nor does the non-profit Sudden Cardiac Arrest Foundation’s main treatment page on the LifeVest. (It’s worth noting that ZOLL donates to the foundation). Even a Wikipedia page contains no information on risks.

One of the nation’s biggest related non-profits, the American Heart Association, doesn’t seem to have much consumer-facing content on the vest, but it did write a news story about the AHA’s 2016 scientific statement on wearable defibrillators. It includes this eye-opening quote from Bradley Knight, MD, director of the Bluhm Cardiovascular Institute at Northwestern Medicine:

“Risks are low, even exceedingly low,” Knight said. “Sometimes we’re too compulsive asking for randomized clinical trial data when there is little downside and it works.”

The story doesn’t disclose Knight received more than $185,000 in industry fees in 2013-2015, according to the latest available numbers from Dollars for Docs.

How well does it work?

Complicating matters, the scientific research so far is unclear about whether the device definitively works better than standard medical treatment. As the AHA’s scientific statement notes:

“At the time of this writing, there are no completed randomized trials of wearable cardiac defibrillator (WCD) therapy. Thus, no definitive data are available on comparative efficacy versus alternative (or no) treatment.”

[Editor’s note: The following paragraph was updated in April 2018 to add new clinical trial findings.] Long-awaited findings from a two-part trial dubbed “VEST-PREDICTS” added some clarity, at least for heart attack patients. Presented at the March conference of the American College of Cardiology, the VEST arm of the study measured how frequently the vest prevented sudden death in patients who had an acute heart attack and low “ejection fraction,” which is a measurement of how much blood the heart pumps out. In the group that wore the vest, 1.6% died from sudden cardiac arrest, and in the group that didn’t wear the vest, 2.4% died. That was not a statistically significant difference, despite how Zoll tried to spin the results.

The study was presented 17 years after the device was first approved by the FDA, critics note, and it only applies to a narrow group of patients with a specific heart disease profile, and not for patients like Natalie.

“It’s a terrible device, it’s an awful device,” said University of California, San Francisco cardiologist and associate professor Ethan Weiss, MD. He is not connected to any LifeVest research, although UCSF is heading up the VEST trial. “It was certainly never validated to reduce clinical events.”

He agreed it’s hard to find information that sufficiently informs patients. How does it keep getting used?

“It’s sort of a fairly well-worn story, unfortunately,” he said. “Whether it’s drugs or devices in medicine, there is a lot of preying on the fears of doctors and patients.”

For Rachel Pezzani, who now homeschools her daughter, the negative impact of the LifeVest has lingered. She wants to see it pulled from the marketplace.

“Not only did it affect Natalie mentally, it also affected her emotionally. She was a happy kid,” Pezzani said. “After this ordeal, I swear to God, she has gone into herself. It’s such a climb back uphill.”


  • Ethan Weiss declares no conflicts of interest. Anthony Pearson declares no conflicts of interest in 2016-2018. In 2015, he received $205 from several drug companies. John Mandrola has served as a speaker for Medtronic. In 2015, he received $2,653 in fees from several drug and device companies.

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