AMUNDSEN tested whether starting a PCSK9 inhibitor immediately, rather than after the usual weeks of stepped oral therapy, improves outcomes after myocardial infarction. It randomised 2,161 patients with high-risk STEMI or NSTEMI at 48 sites in six countries to evolocumab starting before percutaneous coronary intervention plus standard care, or standard care alone.
The lipid result was emphatic. The primary outcome, LDL under 55 mg/dL with at least a 50% reduction at twelve months, was met by 82% on evolocumab against 40% on standard care (adjusted odds ratio 5.54, 95% CI 4.50-6.82). Median LDL at six weeks was 16 mg/dL against 56. The clinical endpoint was not: all-cause death or unplanned cardiovascular hospitalisation occurred in 14.6% against 15.4% (adjusted odds ratio 0.94, 95% CI 0.73-1.19).
This is a useful negative. It argues against acute pleiotropic benefit from PCSK9 inhibition beyond lipid lowering, and it says that within one year the speed of reaching target does not itself buy events. It does not argue against PCSK9 inhibitors, whose benefit accrues over years. The practical reading is that there is no need to reach for one in the catheter laboratory, and time to establish oral therapy and see who genuinely needs escalation.
- 82% reached the LDL target vs 40% with standard care
- Median LDL 16 mg/dL at six weeks vs 56 mg/dL
- Death or unplanned CV hospitalisation 14.6% vs 15.4% (OR 0.94)
- No case for starting a PCSK9 inhibitor in the catheter laboratory
The statistics, in plain English
The odds ratio of 5.54 for reaching target and 0.94 for clinical events, in the same trial, is the clearest possible demonstration that a surrogate endpoint and an outcome are different things. The clinical interval, 0.73 to 1.19, is wide enough to contain a modest benefit, so this is not proof of no effect; but a trial powered to show a large early benefit did not find one, and that is informative about timing rather than about PCSK9 inhibition itself.
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