A Brief Reply to Wil Ward and the Wearable Cardiac Defibrillator (LifeVest)

As a gift to the paying subscribers, I will offer some additional thoughts regarding Dr. Ward’s excellent commentary yesterday.

Wil was correct in his assessment that seeing something work is not enough evidence. Back in the 1980s-90s I recall seeing an antiarrhythmic drug suppress PVCs in a post-MI patient. But it turned out that when we treated large numbers, the average effect was harm. See the CAST trial.

He is also correct that the way to know what works is through the randomized controlled trial.

When that was done in the VEST trial with wearable cardiac defibrillator (WCD), it did not provide an average benefit to patients who were most likely to be benefited.

What does that mean for the WCD? Should we conclude that it never works? Or that it should be taken off the market? If a drug failed to provide benefit, and it had risks (in this case inappropriate shocks), it would be taken off the market.

But I think things are more subtle here. Let me explain.