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Ahmad Masri @MasriAhmadMD
, 18 tweets, 10 min read Read on Twitter
1/ A long thread on LifeVest. I promise it will be entertaining. If you find any inaccuracies please let me know.

Paper of VEST published here - will discuss background to WCD and #VEST but not the trial itself…
2/ In 2001, FDA gave approval to Lifecor for the first WCD. Later Lifecor was acquired by Zoll (2004 agreement, 2006 acquisition). Zoll maintains a registry for prescribed LifeVests. But lets go back to the FDA approval process.
3/ Lifecor presented 2 separate prospective studies to the FDA; WEARIT and BIROAD. FDA asked for both to be combined into 1 study, and each study representing a subgroup. A total of 289 patients were included.
4/ WEARIT (177 pts, NYHA ≥ III, LVEF< 30%). BIROAD (112 pts, MI c/b VT, EF < 30% 3 days after MI, syncope, SCD 48 hours after MI but not candidate for ICD or refused it, or VT post CABG).
5/ follow up: 901 patient-months, 6 out of 8 VT/VF treated by WCD. This was COMPARED to HISTORICAL controls who suffered SCD at home and called emergency services, in whom successful SCD resuscitation was 25%.
6/ Also, only 27% of patients in WEARIT were taking a beta-adrenergic antagonist, 34% were on anti-arrhythmic medications, and 45% were on inotropes.
7/FDA concluded - WCD device had greater efficacy than bystander resuscitation in the historical control group - thus was approved
8/So WCD was approved and ready for commercialization and many iterations over the years. Zoll kept a database which was used for publication purposes. Since then, many studies have been published. Few independent reports as most used the Zoll database.
9/ By our team's count, only 6 studies totaling 710 patients, of which 74% were from a single center study, were independent studies (no Zoll COI, Zoll funding, or commercial database use) out of around 28 studies with 33K patients.
10/ In 2016, AHA expert consensus gave IIB rec for WCD. In 2017, ACC/AHA/HRS gave IIa rec for WCD in secondary prevention when ICD removal is required and IIb rec for all other scenarios, including primary prevention.
11/ Why no RCTs? In 2007, NIH funding for VEST (NCT01446965, 5U01HL089458) started – continued until 2011 for data coordination. Zoll sponsored the other 80% initially, then sponsored the whole trial.
12/Slow enrollment led to changing end-point from all-cause mortality at 60 days (n=4506) to SCD or non-sudden death due to VT This happened after enrolling 244 patients (year 2010).
13/ target n changed to 1900. On, target n then changed again on 6/15/16 to 2300 (in NEJM paper – “In October 2015, on the basis of lower-than-expected device wear time and without the inspection of outcome differences according to trial group”
14/ You might wonder then why did we practice for that long without evidence? IRIS & DINAMIT both showed no overall mortality benefit to early ICD implantation despite reduced arrhythmic mortality because reduction in SCD was offset by competing non-arrhythmogenic causes of death
15/ To Zoll this was all going well. This is taken from a Zoll business presentation available here (… )
Note that the report states up to 2015, 200,000 patients have been protected
thoughts? can go here for some statistical take on this
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