Background: Atrial fibrillation (AF) is common in patients with cardiac amyloidosis (CA) and is a significant risk factor for heart failure hospitalization and thromboembolic events. Objective: to investigate the atrial electro-functional predictors of incident AF in CA. Methods: A multicenter, observational study performed in 4 CA referral centers including sinus rhythm patients with light-chain (AL) and transthyretin (ATTR) CA undergoing electrocardiogram (ECG) and cardiac magnetic resonance (CMR). The primary endpoint was new-onset AF occurrence. Results: Overall, 96 patients (AL-CA: n=40; ATTR-CA n=56) were enrolled. During an 18-month median follow-up (Q1-Q3:7-29), 30 patients (29%) had incident AF. Compared with those without, patients with AF were older (79 vs 73 years, p=0.001) and more frequently with ATTR (73% vs 27%, p<0.001), ECG inter-atrial block (IAB), either partial (47% vs 21%, p=0.011) or advanced (17% vs 3%,p=0.017), and lower left atrium ejection fraction (LAEF) (29% vs 41%, p=0.004). Age (HR=1.059; 95%CI 1.002-1.118,p=0.042), any type of IAB (HR=2.211; 95%CI 1.03-4.75, p=0.041) and LAEF (HR=0.967; 95%CI 0.936-0.998, p=0.044) emerged as independent predictors of incident AF. Patients exhibiting any type of IAB, LAEF<40%, and aged>78 years showed a cumulative incidence for AF of 40% at 12 months. This risk was significantly higher than that carried by one (8.5%) or none (7.6%) of these three risk factors. Conclusions: In patients with CA, older age, IAB on 12-lead ECG and reduced LAEF on CMR are significant and independent predictors of incident AF. A closer screening for AF is advisable in CA patients carrying these features.
