You don't need to be a cardiologist to know that heart attacks kill lots of people. But unless you're a cardiologist you may not know that many people remain at high risk for a second serious heart event in the first few months after a myocardial infarction (MI), the technical name for a heart attack. Often that second event isn't another MI, which is caused by a clot blocking one of the vital arteries supplying the heart itself with blood. Instead, after a heart attack the electrical activity of the heart is often disturbed, leading to a much higher risk than before the heart attack of a life-threatening arrhythmia, or dangerous heart rhythm.
Heart patients who are at long-term high risk for serious arrhythmias may have their life saved by the permanent surgical implantation of an ICD (implantable cardioverter-defibrillator), which can deliver a burst of energy to shock the heart back to a normal rhythm. But for a variety of complicated reasons ICDs have not been found to be useful in the immediate period after a heart attack and most experts agree that they should not be implanted for several months after a heart attack.
But because these patients remain at risk for an arrhythmia many doctors have assumed that a non-permanent wearable defibrillator, like the LifeVest from Zoll, would be beneficial. After all, it doesn't require an invasive medical procedure and is less expensive than a permanent ICD.
An interventional cardiologist-- the cardiologists who put in stents and usually treat heart attack patients in the first few hours-- asked an electrophysiologist-- the cardiologists who treat arrhythmias-- whether wearable defibrillators should be used post-MI. Here's what that electrophysiologist, Edward J. Schloss, the medical director of cardiac electrophysiology at Christ Hospital in Cincinnati, OH, replied. It is a good example of how sometimes a procedure or a therapy that seems, intuitively, to be worthwhile and beneficial, may actually not be beneficial at all. Here's his response, which he originally posted on Twitter:
Our group and most thoughtful electrophysiologists do no routinely use wearable defibrillators in the 'waiting period' after MI or PCI. Randomized trials of implantable ICDs in this population do not show benefit-– mortality does not change, only the mode of death. It seems unlikely that a different result would occur with the wearable device. Until a randomized trial shows benefit, I’d be cautious in interpreting the information presented. All reported wearable ICD data is observational registry based and cannot be used to determine efficacy in this population.
Wearable ICDs have real downsides. They are expensive and not consistently coverable by insurance. Many of our patients find out after the decision that they will be left with significant out-of-pocket costs. Even if you consider all registry events as saved lives, the NNT [number needed to treat] and cost effectiveness are unfavorable. They are difficult to wear and interfere with the psychology of recovery. I have seen numerous patients have serious anxiety disorders directly related to the device.
