Insights from the HERA-FIB Registry on Type 1 and Type 2 NSTEMI in AF Patients

Overview

This study analyzed 81.7% of atrial fibrillation (AF) patients with NSTEMI who underwent coronary angiography to differentiate type 1 from type 2 myocardial infarction (MI) using the 4th Universal Definition of MI. It revealed that systematic angiographic evaluation is critical for accurate MI subtype classification and highlighted differences in clinical characteristics and outcomes between the two MI types in AF patients.

Background

The 4th Universal Definition of Myocardial Infarction (UDMI) distinguishes five MI subtypes, with type 1 MI caused by coronary plaque disruption and type 2 MI resulting from oxygen supply-demand mismatch. Differentiating these subtypes is challenging, especially in AF patients, who are often classified as type 2 MI without systematic coronary angiography. Prior studies had low angiography rates, limiting accurate infarct mechanism assessment. The HERA-FIB registry employed a high rate of coronary angiography to better characterize MI subtypes in AF patients presenting with NSTEMI.

Data Highlights

Key Findings

• Systematic coronary angiography was performed in 81.7% of AF patients with NSTEMI, enabling accurate MI subtype adjudication.
• Type 1 MI is characterized by plaque rupture or erosion requiring early coronary intervention, whereas type 2 MI arises from myocardial oxygen supply-demand mismatch without necessarily significant coronary stenosis.
• AF patients are frequently classified as type 2 MI based on troponin dynamics alone, potentially under-recognizing type 1 MI without angiographic data.
• Use of the 4th UDMI criteria combined with angiographic findings improves differentiation between type 1 and type 2 MI in AF patients.
• Clinical outcomes assessed included all-cause mortality, myocardial infarction, stroke, and major bleeding, highlighting the importance of accurate MI subtype classification for prognosis.

Clinical Implications

Clinicians should consider early invasive coronary angiography in AF patients presenting with NSTEMI symptoms to accurately distinguish type 1 from type 2 MI. Reliance solely on troponin elevation and clinical judgment may lead to misclassification, affecting treatment decisions and outcomes. Applying the 4th UDMI criteria alongside angiographic data can guide appropriate management strategies.

Conclusion

The HERA-FIB registry underscores the value of systematic coronary angiography in AF patients with NSTEMI to accurately classify MI subtypes per the 4th UDMI. This approach facilitates tailored clinical management and may improve patient outcomes.

References

1. Thygesen et al. 2018 -- Fourth Universal Definition of Myocardial Infarction
2. Heidelberg Registry of Atrial Fibrillation (HERA-FIB) Study Protocol
3. European Society of Cardiology Guidelines 2015/2020 -- NSTEMI Management