Albuminuria in transthyretin cardiac amyloidosis: Prevalence, progression and prognostic importance

Abstract

AbstractAimsTransthyretin 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 resultsA total of 1181 patients with ATTR‐CA were studied (mean age 78.1 ± 7.9 years; 1022 [86.5%] male; median estimated glomerular filtration rate 59 ml/min/1.73m2 [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).ConclusionsAlbuminuria 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.