Stent Retriever Thrombectomy in Patients With Myocardial Infarction: The Open-Label, Multicenter NATURE Superiority Trial

BACKGROUND: Patients with myocardial infarction and large thrombus burden face greater infarct size and higher mortality; yet, no effective therapy exists for this high-risk subgroup. OBJECTIVES: The purpose of this study was to investigate the effects of stent-retriever thrombectomy in addition to conventional percutaneous coronary intervention (PCI) vs conventional PCI alone on infarct size. METHODS: In this open-label, multicenter, superiority trial, 160 patients with ST-segment elevation myocardial infarction and large thrombus burden at angiography (TIMI [Thrombolysis In Myocardial Infarction] thrombus flow grade ≥3 in infarct-related artery) were consented, and 156 were randomly assigned to undergo stent-retriever thrombectomy followed by conventional PCI or conventional PCI alone. Primary outcome was infarct size extension assessed by area under the curve for creatine kinase-MB. Safety outcome was major adverse cardiovascular events (comprising cardiovascular death, nonfatal myocardial infarction, nonfatal stroke) at 3 and 30 days. RESULTS: Infarct size (creatine kinase-MB area under the curve) was lower in the stent-retriever group (n = 78) vs the conventional group (n = 76) (3,965 IU/L·h; Q1-Q3: 2,480-5,092 IU/L·h vs 5,250 IU/L·h; Q1-Q3: 3,506-7,449 IU/L·h; difference -1,359; 95% CI: -2,231 to -522; P = 0.001). At exploratory cardiac magnetic resonance findings, infarct size was lower in the stent-retriever group (n = 64; left ventricle, 17%; Q1-Q3: 11%-28%) vs the conventional PCI group (n = 59; 28.0%; Q1-Q3: 18%-33%; difference -7.0; 95% CI: -12 to -2.0), whereas left ventricular volumes and ejection fraction did not differ. There were no major adverse cardiovascular events at 3 days and 1 at 30 days in the stent-retriever group vs 2 and 3 major adverse cardiovascular events, respectively, in the conventional PCI group. CONCLUSIONS: Stent-retriever thrombectomy followed by conventional PCI in patients with large thrombus burden undergoing primary PCI ≤8 hours of symptom onset was associated with reduced infarct size vs conventional PCI alone. (NATURE [EnVast as an Adjunct PPCI in Subjects Presenting With STEMI]; NCT04969471).