Importance: The PCSK9 inhibitor evolocumab reduced major vascular events in the Further Cardiovascular Outcomes Research With PCSK9 Inhibition in Subjects With Elevated Risk (FOURIER) trial, yet the types and sizes of myocardial outcomes in FOURIER have not been previously explored.
Objective: To assess the types and sizes of myocardial infarction (MI) and the effect of evolocumab on MI by subtype.
Design, setting, and participants: A prespecified analysis of a multicenter double-blind randomized clinical trial. Patients were randomized to evolocumab or placebo and followed up for a median of 2.2 years. The study included 27 564 patients with stable atherosclerotic disease receiving statin therapy. Clinical end points were evaluated by the Thrombolysis in Myocardial Infarction clinical events committee. Rates presented are 3-year Kaplan-Meier estimates. Data were collected from 2013 to 2016 and analyzed from June 2017 to December 2019.
Main outcomes and measures: Myocardial infarction was defined based on the third universal MI definition, and further classified according to MI type (universal MI subclass, ST-segment elevation myocardial infarction [STEMI] vs non-STEMI) and by MI size (determined by peak troponin level).
Results: A total of 27 564 patients were randomized, with a mean (SD) age of 62.5 (9.0) years, and 20 795 (75%) were male. Of these, 1107 patients experienced a total of 1288 MIs. Most MIs (68%) were atherothrombotic (type 1), with 15% from myocardial oxygen supply-demand mismatch (type 2) and 15% percutaneous coronary intervention-related (type 4). Sudden death (type 3) and coronary artery bypass grafting-related (type 5) accounted for a total of 21 MIs (<2%). Evolocumab significantly reduced the risk of first MI by 27% (4.4% vs 6.3%; hazard ratio [HR], 0.73; 95% CI, 0.65-0.82; P < .001), type 1 by 32% (2.9% vs 4.5%; HR, 0.68; 95% CI, 0.59-0.79; P < .001), and type 4 by 35% (0.8% vs 1.1%; HR, 0.65; 95% CI, 0.48-0.87; P = .004), with no effect on type 2 (0.9% vs 0.8%; HR, 1.09; 95% CI, 0.82-1.45; P = .56). Most MIs (688 [59.8%]) had troponin levels greater than or equal to 10 times the upper limit of normal. The benefit was highly significant and consistent regardless of the size of MI with a 34% reduction in MIs with troponin level greater than or equal to 10 times the upper limit of normal (2.6% vs 3.7%; HR, 0.66; 95% CI, 0.56-0.77; P < .001) and a 36% reduction in the risk of STEMI (1.0% vs 1.5%; HR, 0.64; 95% CI, 0.49-0.84; P < .001).
Conclusions and relevance: Low-density lipoprotein cholesterol lowering with evolocumab was highly effective in reducing the risk of MI. This reduction with evolocumab included benefit across multiple subtypes of MI related to plaque rupture, smaller and larger MIs, and both STEMI and non-STEMI. These data are consistent with the known benefit of low-density lipoprotein cholesterol lowering and underscore the reduction in clinically meaningful events.
Trial registration: ClinicalTrials.gov Identifier: NCT01764633.