Albuminuria in Transthyretin Cardiac Amyloidosis: Prevalence, Progression and Prognostic Importance

AIMS: Transthyretin cardiac amyloidosis (ATTR-CA) is an infiltrative cardiomyopathy that commonly presents with concomitant chronic kidney disease. Albuminuria is common in heart failure and associated with worse outcomes, but its prevalence and relationship to outcome in ATTR-CA remains unclear. METHODS AND RESULTS: interquartile range: 47-74). Albuminuria was present in 563 (47.7%) patients (499 88.6% with microalbuminuria and 64 11.4% with macroalbuminuria). Patients with albuminuria had a more severe cardiac phenotype evidenced by higher serum cardiac biomarkers (median N-terminal pro-B-type natriuretic peptide NT-proBNP: 4027 ng/L 2173-6889 vs. 1851 ng/L 997-3209, p < 0.001; median troponin T: 69 ng/L 46-101 vs. 48 ng/L 34-68, p < 0.001) and worse echocardiographic indices of systolic (longitudinal strain: -10.0 ± 3.6% vs. -11.6 ± 3.8%, p < 0.001) and diastolic function (E/e': 17.5 ± 6.4 vs. 16.4 ± 6.7, p < 0.001) than those with a normal urinary albumin to creatinine ratio (UACR). Microalbuminuria and macroalbuminuria were independently associated with mortality in the overall population (hazard ratio HR 1.47, 95% confidence interval CI 1.13-1.92, p = 0.005 and HR 1.87, 95% CI 1.15-3.05, p = 0.012, respectively). In a subgroup of patients (n = 349) without concomitant hypertension, diabetes mellitus or chronic kidney disease, albuminuria was also associated with mortality (HR 2.98, 95% CI 1.72-5.17, p < 0.001). At 12 months, 330 patients had a repeat UACR measurement; those in whom UACR increased by 30% or more (n = 148, 44.8%) had an increased risk of mortality (HR 1.84, 95% CI 1.06-3.19, p = 0.030). CONCLUSIONS: Albuminuria is common in patients with ATTR-CA, and more prevalent in those with a more severe cardiac phenotype. Albuminuria at diagnosis and a significant increase in UACR during follow-up are associated with mortality.