Not every bright sign is guidance.
This is not a story about error.
It is a story about certainty.
50,000
deaths per year
From a treatment everyone believed worked.
This is the story of how we believed — and how we were wrong.
The Observation
Patients with frequent PVCs after MI had 2–5× higher mortality.
A massive clinical need. A clear target.
The Response
Antiarrhythmic drugs were developed, FDA approved,
and prescribed to ~200,000 patients per year.
No villain appears in this story.
Everyone acted on the best evidence available.
The Logic That Convinced Everyone
PVCs after MI predict sudden cardiac death
Antiarrhythmic drugs suppress PVCs
Suppressing PVCs should prevent sudden death
Antiarrhythmics save lives in post-MI patients
The chain was logical. The conclusion felt inevitable.
CAST: The Cardiac Arrhythmia Suppression Trial
Finally, someone asked: "Does suppressing PVCs actually save lives?"
Outcome tested: survival. Not assumed. Measured.
The Results: April 1989
Data Safety Monitoring Board stops the trial early.
| Outcome | Drug (n=755) | Placebo (n=743) |
|---|---|---|
| Arrhythmic deaths | 33 | 9 |
| All cardiac deaths | 43 | 16 |
| Total deaths | 56 | 22 |
| Death rate | 7.4% | 3.0% |
The drugs that perfectly suppressed arrhythmias increased mortality by 150%.
Forest Plot: CAST Mortality Results
Every endpoint shows harm. The entire confidence interval excludes benefit.
Note: Forest plot shows outcomes within CAST, not pooled trials. I² = 0% (consistent harm).
The Human Cost
Before CAST, ~200,000 Americans per year received these drugs.
≈ 9,000
excess deaths per year — possibly more
Vietnam War: ~6,000 US deaths/year • These drugs: ~9,000+ deaths/year
For every number, a name we will never know.
Look again.
The Logic — Revisited
PVCs after MI predict sudden cardiac death
Antiarrhythmic drugs suppress PVCs
Suppressing PVCs should prevent sudden death
Antiarrhythmics save lives in post-MI patients
The assumption that suppressing the marker would fix the outcome was never tested.
What Went Wrong: The Surrogate Trap
PVCs were a marker of damaged tissue, not a cause of death
The drugs had proarrhythmic effects — triggering deadlier rhythms
The surrogate improved while the outcome worsened — a dissociated surrogate
The surrogate did not lie. We asked it the wrong question.
The Lessons for Evidence Synthesis
Biological plausibility is not proof
A logical mechanism doesn't guarantee the expected effect.
Surrogate endpoints can mislead
Improving a biomarker doesn't prove improvement in outcomes.
Only randomized trials establish causation
Observational data cannot prove intervention effects.
Consensus is not evidence
200,000 prescriptions, FDA approval, and guidelines were all wrong.
This is why we do meta-analysis: to see past apparent truths.
What appears certain may be wrong.
What everyone believes may be false.
Methods exist so patients do not pay for our confidence.
This is why you are here.
Not every bright sign is guidance.
Methods protect patients from our confidence.