Predictors of type 1 myocardial infarction in patients presenting with atrial fibrillation and suspected acute coronary syndrome

Background: Atrial fibrillation (AF) and atrial flutter (AFLUT) are common in patients presenting to the emergency department (ED) with suspected acute coronary syndrome (ACS) and severely complicate the identification of patients with type 1 myocardial infarction (MI).

Purpose: To identify predictors of type 1 MI requiring target lesion revascularization (TLR) in patients with AF/AFLUT undergoing coronary angiography (CA) because of suspected ACS.  

Methods: Between 1/2014 and 11/2021 we retrospectively identified patients who underwent CA due to suspected ACS at two tertiary centers in Munich, Germany. Patients with ST-elevation MI (STEMI) were excluded. AF/AFLUT was automatically identified and manually verified.  The primary endpoint of the study was type 1 MI requiring TLR. The secondary endpoint was intrahospital mortality. The association between risk-identifiers and TLR was tested using logistic-regression analysis. Following subgroups were considered: angina pectoris, age ≥ 70 years, all cardiovascular (CV) risk factors, left-ventricular ejection fraction (LVEF) < 30% high sensitivity Troponin (hsT) >0.052 ng/ml and ischemic ECG changes. The interaction between subgroups and AF/AFLUT for identifying patients with type 1 MI was estimated by including the product of the subgroup identifier with AF/AFLUT in the multivariable model. 

Results: We identified 4,790 patients (age 73±18 years, 1,451 females; 30.3%) with available ECG recordings, who underwent diagnostic CA due to suspected ACS. In 3,126 (65.3%) cases a type 1 MI with need for TLR was identified. Patients with AF/AFLUT received TLR significantly less often than patients without AF/AFLUT (59.5 vs. 66.3%, p<0.001), which remained significant after adjustment for angina, age, kidney failure, arterial hypertension and gender (OR 0.63, 95%CI 0.53 – 0.75, p<0.001). After adjustment for the same factors, patients with AF/AFLUT did not suffer from higher mortality (OR 1.13 95%CI 0.77-1.64, p=0.533). There was no significant interaction between subgroups and AF/AFLUT for prediction of type 1 MI requiring TLR (Figure). 

Conclusion:  AF/AFLUT more commonly leads to unnecessary CA in patients presenting to the ED with suspected ACS. Angina pectoris, male sex, age ≥ 70 years and presence of CV risk factors are the most important predictors of type 1 MI requiring TLR in both patients with and without AF/AFLUT undergoing CA because of suspected ACS.