Prognostic Value of the 6-Minute Walk Test and Clinical Characteristics of Patients With Transthyretin Amyloid Cardiomyopathy

Abstract

Background: In transthyretin amyloid cardiomyopathy (ATTR-CM), the assessment of functional capacity is of great importance. A distance < 300m covered in the 6-minute walk test (6MWT) is linked to a poorer prognosis in heart failure (HF) patients. However, in ATTR-CM, this association is not well-established, particularly among its various presentations and variants. Objectives: To evaluate functional capacity and, the prognostic value of the 6MWT in patients with ATTR-CM and to identify their clinical characteristics according to the type of ATTR-CM. Methods: This was a retrospective, single-center study that included patients with a confirmed diagnosis of ATTR-CM who performed the 6MWT. Median follow-up was 19 months (8 – 29). The significance level was set at P < 0.05. Results: A total of 32 patients were analyzed; 59.4% had the hereditary form (ATTRh), of which 63.2% were Val142Ile. Mean left ventricular ejection fraction (LVEF) was lower in the ATTRh group when compared to the wild-type form (ATTRwt) [42 ±11 versus 52± 9 %; p = 0.029]. Median distance walked in the 6MWT was 328 m (269 – 397; IQR) in ATTRwt and 304 m (246 – 387; IQR) in ATTRh, with no difference between groups (p = 0.833). In patients with a distance <300 m in the 6MWT, survival was lower (28.8 vs 36.3 months; p = 0.041). Conclusions: A distance <300 m walked in the 6MWT was linked to shorter event-free survival in patients with ATTR-CM. Functional capacity of most patients was very low, and no differences were observed in the distance covered between the wild-type form and the hereditary form of ATTR.