Higher systemic AL amyloidosis scores at diagnosis predict development of new-onset atrial fibrillation or flutter

Background Light chain cardiac amyloidosis (AL-CM) is an infiltrative cardiomyopathy associated with significant morbidity and mortality. Early diagnosis and risk stratification is critical for prognostication and management, particularly identifying patients most likely to need heart transplants. The systemic light chain amyloidosis (sAL) score is derived from echocardiographic parameters: relative wall thickness (RWT), E/e' ratio, global longitudinal strain (GLS), and tricuspid annular plane systolic excursion (TAPSE) and is validated in the diagnosis of AL-CM [1]. Its prognostic value for development of atrial fibrillation, progression of heart failure, and hospitalizations remains unclear. This study evaluates the association between the sAL score, arrhythmias, and functional outcomes in patients with confirmed AL-CM. Methods A retrospective review of patients seen at our hospital, with confirmed AL-CM diagnosed between June 2014 and October 2021 was conducted on an IRB-approved protocol. The sAL score was collected at the time of diagnosis. Binary outcomes were evaluated using a weighted Mann-Whitney U test, with effect size calculated as r=Z/sqrt(N). Ordinal and continuous outcomes were analysed using weighted Spearman correlation, with Spearman’s rho reported as the effect size. Results 37 patients with AL-CM were included (51.4% male), with a median age of 70 years [IQR 66–76], a median sAL score of 5 [IQR 3–6], and a median left ventricular ejection fraction (LVEF) of 55% [IQR 50–60] at diagnosis. 24 patients had their AL-CM diagnosed by cardiac MRI and positive Congo red on peripheral biopsy (e.g., fat pad); the other 13 had positive endomyocardial biopsy. 22 patients had sAL scores ≥ 5 with overall survival of 17/22 (77.3%) and median follow-up of 53 months. 15 patients had sAL scores < 5 with overall survival of 14/15 (93.3%) and median follow-up of 57 months. 4 patients had atrial fibrillation or flutter at diagnosis. 6 patients developed atrial fibrillation or flutter with a median onset of 15 months after diagnosis. Higher sAL scores at diagnosis were associated with development of new-onset atrial fibrillation or flutter (median sAL 4.5 vs 5, p = 5.75×10^-10, r = 1.02), heart failure hospitalizations (median sAL 5 vs 5, p = 1.94×10^-6, r = 0.78), and ≥30% eGFR decline at 12 months (median sAL 4.5 vs 6, p=8.69×10^-24, r = 1.65). Higher sAL scores were moderately correlated with NYHA class (rho = 0.44, p = 0.00378) and strongly correlated with diastolic dysfunction grade (rho = 0.549, p = 9.99×10^-6) but not associated with change in LVEF (p = 0.51 and p = 0.62, respectively). Conclusion sAL scores of ≥5 at diagnosis were associated with worse functional and clinical outcomes in patients with proven AL-CM. These findings suggest the sAL score predicts electrophysiological changes, supporting its potential role in early risk stratification and disease monitoring.