Transthyretin Cardiac Amyloidosis in the Black Population: A Ten-Year Experience

Abstract

Introduction Transthyretin (ATTR) cardiac amyloidosis (CA) is becoming increasingly recognized as an underlying pathology of heart failure with preserved ejection fraction (HFpEF) in elderly patients. One in 25 African Americans are carriers of the hereditary variant (ATTRv) Val-122-Ile point mutation, increasing the risk of developing ATTR-CA. Age-related wild-type (ATTRwt) is the most common cause of ATTR-CA overall, seen most often in white males. We present the racial distribution of ATTR-CA at our institution from 2008-2018, focusing on the black subpopulation. Methods This is a retrospective review of patients with ATTR-CA seen between 2008 and 2018 at the Cleveland Clinic. Diagnosis of ATTR-CA was established via endomyocardial biopsy or non-biopsy protocol with technetium pyrophosphate scintigraphy. Genetic typing was obtained when possible. Results Of 350 patients with ATTR-CA, 110 (31%) identified as racially black or African American. In the black population with available genetic testing (n = 96), 76% of cases were due to Val-122-Ile ATTRv and 22% were due to ATTRwt. Variants Asp-18-Asn and Glu-54-Gln were also represented with one case each. Average age at diagnosis in the black subpopulation was 75 ±9 years and 78% of patients were male. History of hypertension was seen in 83% of patients, and diabetes mellitus was seen in 38%. Carpal tunnel syndrome was present in 46% of patients. There were no statistically significant differences in demographics, clinical or lab parameters between blacks with ATTRv Val-122-Ile versus ATTRwt. Conclusions Over the course of a decade, black patients accounted for nearly one-third of all patients with ATTR-CA seen at our institution. The majority had hereditary ATTR due to the Val-122-Ile mutation, but nearly one quarter had ATTRwt. Additionally, there were two rarer mutations found. Current estimates of the prevalence of ATTR-CA in the black population focus on those with the Val-122-Ile variant at risk for development of hereditary ATTR, but do not account for blacks who may develop ATTRwt. The significant prevalence of ATTRwt in our cohort suggests ATTR-CA may be more prevalent in the black population. With accessibility to non-invasive diagnostic methods, recognition of ATTR-CA in black patients is critical as therapies become available for this progressive disease.