Atrial Fibrillation Long Term Outcomes

Introduction Coronary embolism (CE) is a relatively rare but significant cause of non-atherosclerotic acute myocardial infarction (AMI), representing about 3% of all AMI cases, though it is likely underdiagnosed. CE is associated with worse clinical outcomes than traditional atherosclerotic AMI, showing increased rates of cardiac death and cerebrovascular events. Atrial fibrillation (AF) is the primary underlying cause of CE, cited in 28%-73% of cases across large series. Despite AF's central role, comprehensive data detailing the clinical, biochemical, echocardiographic, angiographic characteristics, and outcomes of CE specifically linked to AF remains limited. This study aims to address this knowledge gap by retrospectively evaluating patients with AF-related CE (AF CE) and non-AF CE, characterizing their differences and identifying outcome predictors.

Methods From January 2008 to Dicember 2024, consecutive patients admitted to a tertiary care cardiology unit and meeting both the Fourth Universal Definition of AMI and either definite or probable CE per Shibata's criteria were retrospectively included. Shibata's classification involves major and minor angiographic and clinical criteria to establish the likelihood of CE. Definite CE is diagnosed with a combination of major and minor criteria, while probable CE requires fewer criteria. Cases with evidence of atherosclerotic thrombus, prior revascularization, coronary anomalies like ectasia, spontaneous coronary artery dissection, or stress cardiomyopathy were excluded.

Coronary Embolism Definition

The Shibata criteria define CE based on:

Major criteria: angiographic embolism signs unrelated to atherosclerosis, multisite CE, systemic embolism excluding left ventricular thrombus from STEMI.

Minor criteria: non-significant coronary stenosis (<25%), embolic source identified by imaging, and risk factors like AF, dilated cardiomyopathy, rheumatic valve disease, prosthetic valves, recent cardiac surgery, coagulation disorders, patent foramen ovale, or atrial septal defect.

Coronary Arteriography All patients underwent invasive coronary angiography, independently reviewed by two specialists. Stenoses were visually assessed according to recognized grading systems.

Echocardiography Transthoracic echocardiography was performed following contemporary guidelines, evaluating left atrial and ventricular size and function, and left atrial strain using speckle tracking with standardized software (Philips).

Cardiac Magnetic Resonance (CMR) CMR was performed in patients initially diagnosed with MINOCA (Myocardial Infarction with Non-Obstructive Coronary Arteries) based on standard protocols, evaluating for subendocardial or transmural late gadolinium enhancement and focal myocardial edema to support CE diagnosis.

Atrial Fibrillation Definition AF was diagnosed as per ESC guidelines, requiring over 30 seconds of rhythm without P waves and irregular RR intervals. Both history of AF and new-onset AF during hospitalization or follow-up qualified for classification into the AF CE group.

Outcomes

Two types of outcomes were evaluated:

In-hospital outcomes: composite of heart failure, cardiogenic shock, ventricular arrhythmias, stroke, or death.

Long-term outcomes: composite of reinfarction, systemic embolism, stroke, cardiac or all-cause mortality.

Ethics The study protocol was approved by an independent ethics committee, with a waiver of informed consent, justified under the principles of the Declaration of Helsinki (reference n° 3318-0000257).

Statistical Analysis Categorical variables were presented as frequencies and percentages, continuous variables as means ± standard deviations. AF CE and non-AF CE groups were compared using Chi-square or Fisher's exact tests for qualitative variables, and parametric or non-parametric tests for quantitative variables depending on distribution normality (Kolmogorov-Smirnov test). For in-hospital outcomes, univariable logistic regression was performed to identify associated variables, followed by multivariable stepwise forward logistic regression for variables with p < 0.1. Long-term outcomes were assessed using univariable Cox regression and multivariable stepwise forward Cox regression for significant variables. Kaplan-Meier survival analyses and log-rank tests evaluated long-term outcome differences. SPSS version 20 (IBM) was used, with p < 0.05 considered statistically significant.