OBJECTIVES

Transthyretin Amyloid Cardiomyopathy (ATTR-CM) is a rare, progressively debilitating, fatal disease. We aimed to develop an algorithm using the dispensed daily doses of loop diuretics to estimate survival of patients with ATTR-CM according to the disease severity.

METHODS

A cohort of 4815 individuals (mean age of 78.7 (10.0) years old, 66.9% of men) diagnosed with ATTR-CM between 2011 and 2017 was constituted using real-world data from the SNDS nationwide database. We used a severity index based on the daily dose of loop diuretics (bumetanide or furosemide) to construct a 4-level classification ranking patient’s congestive symptoms of ATTR-CM: minor (furosemide<20 mg or bumetanide<0.5 mg); mild (furosemide=20-59 mg or bumetanide=0.5-1.4 mg); moderate (furosemide: 60-119 mg or bumetamide=1.5-2.9 mg); severe (furosemide≥120 mg or bumetanide≥3 mg). Daily dose was estimated by dividing the total dose dispensed over the six months period after diagnosis by 180 days, for patients still alive at six months. To avoid immortal time bias, the period between diagnosis and death was considered for patients who died in the six months, and for patients who had no dispensing of diuretics after diagnosis, the six months period before diagnosis was used.

RESULTS

The median survival time of the study population was 33.7 months. Deaths happened rapidly after diagnosis as 1,357 individuals (28.2%) died a year after diagnosis and 1,717 (35.7%) died before reaching two years of survival. Survival was inversely linked with loop diuretics daily dose (median survival was 5 years for minor severity assigned individuals vs. 13.9 months for severe assigned individuals).

CONCLUSIONS

ATTR-CM has a poor prognosis which is related to the patients’ severity measured indirectly by the daily dose of diuretic they received. These data illustrate the severity of the disease in real life and prompts the use of disease modifying therapy as soon as possible after the diagnosis.