September 26th, 2012

Treading Water During the Post-MI Waiting Period


A 60-year-old man was admitted to the hospital with an inferior ST-segment-elevation MI, having arrived an hour after the onset of chest pain. He underwent primary PCI (door-to-balloon time, 30 minutes) and had no signs of heart failure. However, an echocardiogram performed the next day revealed multiple regional wall-motion abnormalities and a left ventricular ejection fraction of 33%.

The doctors recommended that the patient wear a Zoll LifeVest for 90 days and then return for a repeat assessment of his LVEF to determine whether he may benefit from an ICD. The patient was told that their practice routinely uses the LifeVest during this period after an MI for all patients with a depressed LVEF, until they can be assessed further.


1. Does your institution use the LifeVest strategy routinely during the waiting period after an MI?

2. What evidence do you use to support or eschew the strategy?


James Fang, MD

October 3, 2012

Mortality risk is high during the first few months after acute MI. Routine implantation of an ICD in high-risk patients after acute MI does not lower their overall mortality risk but does reduce the risk for arrhythmia-related death (see the DINAMIT trial).

It is on this basis that some recommend the LifeVest as “bridge” therapy during this high-risk period. The LifeVest may be particularly attractive because, although it cannot reliably address bradyarrhythmias, it is not invasive like an ICD. Also, the risk for sudden death after MI decreases with time-dependent improvements in LVEF from revascularization and meds, and the LifeVest does not commit a patient to potentially unnecessary “permanent” therapy. However, even though the vest may prevent sudden death from arrhythmia, it may not reduce overall mortality risk, given that the extent of the acute infarction may be the key determinant in the patient’s outcome (again, see DINAMIT).

The electrophysiologists at my institution will offer the LifeVest to post-MI patients who appear to have, in addition to a low LVEF, major risk factors for sudden cardiac death (e.g., significant nonsustained ventricular arrhythmias, heart failure, inability to tolerate meds due to bradycardia or hypotension) during the first 40 days after acute MI, when ICD implants are not covered by CMS reimbursement. However, no randomized data support this practice; nor, arguably, does the DINAMIT trial. To my knowledge, the largest published study of the LifeVest is from an observational cohort.

Our electrophysiology service is not routinely asked to provide post-MI assessment of risk for SCD; in general, that remains the purview of our CCU faculty.  Some institutions pursue further risk stratification with Holter monitoring, heart-rate variability (HRV) testing, electrophysiology studies, signal-averaged EKG, etc. Notably, in the DINAMIT trial, additional factors (beyond LVEF) were used to identify patients at high risk for SCD (e.g., depressed HRV and increased heart rate).

Finally, after an acute MI, medical therapy must be optimized (statin, beta-blocker, ACE inhibitor, aldosterone antagonist), and LV function should be reassessed over time.


Harlan M. Krumholz, MD, SM

October 10, 2012

For a month the patient was bothered by the vest during sleep and by the high price tag. He switched doctors, and an equilibrium radionuclide angiocardiography (ERNA) scan was ordered; it revealed an LVEF of >40%. The vest was discontinued, and the patient finally was able to get a good night’s sleep.

12 Responses to “Treading Water During the Post-MI Waiting Period”

  1. In the Wearable Defibrillator Investigative Trial/Bridge to ICD in Patients at Risk of Arrhythmic Death (WEARIT/BIROAD) study ~ 300 patients with NYHA class III or IV heart failure and LVEF <30 percent or at high risk for SCD after MI or CABG (and not receiving ICD for up to four months) were given Lifevest.

    Six successful defibrillations occurred in four patients (1.4 percent of total patients) during 3 months of follow up. However ~25% of patients withdrew due to size and weight of the monitor. However, there were also 6 inappropriate shocks.

    Obviously DINAMIT introduced the 40 day recommendation. I do not know the frequency pattern of prescribing Lifevest- but do not
    feel it is recommended

  2. David Powell , MD, FACC says:

    Even if LV function fails to improve, this patient with an ischemic cardiomyopathy, EF< 30, no CHF, and no NSVT does not satisfy evidence-based criteria for an ICD. Also note that eplerenone markedly reduced sudden death in EPHESUS (population similar to the aforementioned study).

    Use of the Vest is variable, increasing with decreasing EF and NSVT. Evidence is as cited.. minimal, particularly since the medical therapy was suboptimal.

  3. Stephen Hansen, md says:

    Any data pertinent to Vest use in a 40y.o. cauc. man with nl. EF and 1 episode of syncope and NSVT due to sarcoidosis by MRI and PET.

  4. Jean-Pierre Usdin, MD says:

    Life vest is …on your chest!

    In France (to my knowledge) we have not this wearable defibrillator (but I heard of).
    However, I am sure when it will be available a lot of patients suffering from PVC’s sustained or not, with ischemic cardiomyopathy or not, with EF<30%or not (…add what you imagine) will ask for this jacket.
    So finally it will quickly turn in Titanic's live saver (not enough for everyone!)
    more seriously is there anybody who can tell the weight, the manufacturer,the price but the references of the WEARIT/BIROAD study. It looked to me so innovative

  5. Jean-Pierre,
    Here is the reference for the WEARIT study, done out of Philadelphia (Pacing Clin Electrophysiol. 2004 Jan;27(1):4-9). The manufacturers claim that the device weighs 1.5 kg, and delivers 285 Joules.
    However, compliance is a major issue- a poster presentation at ACC in 2010 quoted mean daily use of ~20 hours/day and 14% stopped using it because of weight and size (Chung et al J Am Coll Cardiol. 2010;56(3):194).

  6. Jean-Pierre Usdin, MD says:

    thank you
    JP U

  7. As further elaboration, this patient had no episodes of PVCs, NSVT – this was purely used because of his EF immediately post-MI. I wondered about consent. The man was told that the Vest was essentially an insurance policy for him. To be safe. I am conveying this third hand – but that is how the patient perceived the content of the discussion.

  8. This is a therapy awaiting data and guidelines. In my view, its use is often due to concerns of malpractice and many patients pay thousands of dollars out of their own pockets.

  9. David Powell , MD, FACC says:

    It is also difficult to oppose the use of the Vest once any physician has made a positive recommendation. It becomes an emotional issue for many patients, and one must carefully assess a patient’s understanding. I believe this is part of Dr. Usdin’s point. Its like taking the supplemental oxygen off a patient having a heart attack ( despite no benefit and possible harm in well oxygenated patients).
    . As far as “consent”, the major issue is inappropriate shocks. But what requires consent other than procedures and trials? How about the use of amiodarone for afib (not FDA approved and with potential toxicity)?

  10. Thanks for the comments. The patient has not had any events but the inconvenience and discomfort of the vest has been substantial. The vest has also caused some worry and anxiety. There is also a cost to the vest, as Minnow noted, though I am not sure if the patient bore any of it.

  11. Society pays $3,000 monthly. We do not know NTT since no study has ever showed Lifevest improves mortality.It is not “insurance” but untried therapy; admittedly with relatively low downside other than cost. Let’s await the ongoing RCT’s listed at and then use.

  12. Edward Bender, MD says:

    Here’s an anecdote. 45 year old with massive MI requiring emergent CABG. EF 15% going into and coming out of surgery and discharge. Optimum medical therapy. No ectopy in hospital. Went home with Life Vest. Patient lives in very rural area and has no cell phone access or any other form of connectivity for the device. 10 days after discharge the Life Vest alarms every couple of hours. The patient defeats the alarm and the subsequent shock at least 3 times. Finally, when he passes out, the wife calls 911. Dead at the scene. Record shows multiple episodes of non-sustained and sustained v tach finally degenerating into v fib. This proves nothing except that any device that the patient has control over is defeat-able.