Type 1 and type 2 NSTEMI in atrial fibrillation: insights from the HERA-FIB registry

Background Differentiating type 1 vs. type 2 NSTEMI in atrial fibrillation (AF) is difficult because hs-cTn fluctuations and comorbidity blur ischemic vs. supply–demand injury. Purpose To quantify the prevalence, clinical features, and outcomes of type 1 and type 2 NSTEMI in AF patients undergoing coronary angiography, and evaluate the diagnostic yield of invasive evaluation in acute myocardial injury. Methods Retrospective analysis of the Heidelberg Registry of Atrial Fibrillation (HERA-FIB) including 438 consecutive AF patients with suspected ACS who underwent invasive angiography during index hospitalization (2009–2020). NSTEMI subtypes were adjudicated per the Fourth Universal Definition of MI. The primary endpoint was a composite of all-cause death, MI, stroke, or major bleeding. Results Of 438 patients, 312 (71.2%) had type 1 NSTEMI, 100 (22.8%) type 2 NSTEMI, and 26 (5.9%) acute myocardial injury. Type 2 NSTEMI showed preserved LVEF and less obstructive CAD yet similar long-term risk vs. type 1 for the composite endpoint (36.0% vs. 40.1%) and recurrent MI (12.0% vs. 9.6%). Acute myocardial injury had the highest mortality (57.7%) and frequent multivessel disease. Conclusions In symptomatic AF, type 1 NSTEMI is common and often missed without angiography, which enables accurate diagnosis and revascularization. Type 2 NSTEMI also carries substantial risk, and significant CAD is frequent even with non-ischemic injury, underscoring the need for improved diagnostic tools and tailored prevention.Distribution of Final Diagnoses. KM Estimates of Composite Endpoint.