Prognostic impact of atrial fibrosis detected by cardiac magnetic resonance in patients affected by cardiac amyloidosis

Abstract Background Cardiac amyloidosis is a cardiac storage disease caused by the progressive extracellular deposition of misfolded proteins in the myocardium. Atrial fibrosis is a parameter easily detectable by cardiac magnetic resonance (CMR), with good reproducibility. While its association with adverse outcomes in various cardiovascular conditions has been estabilished, its prognostic value in cardiac amyloidosis remains unclear. Purpose The objective of this study was to assess the correlation between CMR-detected atrial fibrosis and demographic, clinical, and instrumental parameters in patients affected by cardiac amyloidosis. Additionally, the study sought to evaluate the prognostic significance of atrial fibrosis in predicting adverse outcomes, including mortality, acute heart failure (AHF), and arrhythmias. Methods A cohort of 80 patients with cardiac amyloidosis was stratified into two groups based on the presence of atrial fibrosis detected via CMR: 39 patients without atrial fibrosis and 41 patients with atrial fibrosis were included, with a median follow-up duration of 154 weeks (IQR 157). Baseline demographic, clinical, echocardiographic, and CMR parameters were compared between the groups. Additionally, multivariate Cox regression analysis was performed to identify predictors of all-cause mortality, cardiovascular mortality (CVM), and AHF. Results The median age of the cohort was 73 years, with a higher prevalence of male sex (78.8%). The presence of atrial fibrosis was associated with worse functional status (NYHA class III/IV), and higher levels of biomarkers such as creatinine and hs-cTNT. Echocardiographic parameters showed significant differences in right ventricular function, and higher left atrial area in the fibrosis group. The presence of atrial fibrosis was also linked to higher LV mass and LV ejection fraction impairment. During follow-up, patients with atrial fibrosis experienced higher rates of adverse events, including AHF, syncope, and CVM. Cox regression analysis revealed that atrial fibrosis (HR: 2.66, 95% CI: 1.11–6.36, p=0.028) was an independent predictor of all-cause mortality, alongside age (p0.001), stroke (p=0.024), and NYHA class (p=0.030). For CVM, diabetes mellitus (p=0.002) was identified as a significant predictor. Conclusion CMR-detected atrial fibrosis in patients with cardiac amyloidosis is associated with adverse clinical outcomes, including increased mortality and AHF. The presence of atrial fibrosis resulted an independent predictor of all-cause mortality at multivariate analysis. According to these results, a routine assessment of atrial fibrosis should be encouraged when performing CMR in patients with cardiac amyloidosis, whether suspected or confirmed. Actually, this parameter can provide valuable prognostic information in this population. Further studies are needed to explore potential therapeutic strategies targeting atrial fibrosis to improve patient outcomes.Multivariable Cox Regression Analysis Kaplan-Meier curves for atrial fibrosis