Association of the V122I Transthyretin Amyloidosis Genetic Variant With Cardiac Structure and Function in Middle-aged Black Adults: Coronary Artery Risk Development in Young Adults (CARDIA) Study

Question  Is there an association between the common transthyretin (TTR) genetic variant V122I and adverse cardiac mechanics among middle-aged Black adults without symptomatic heart failure?

Findings  In this population-based cohort study of 875 Black adults, there was a significant association of the TTR V122I variant with worse left ventricular structure and cardiac mechanics at a mean age of 54 years.

Meaning  In Black middle-aged adults with the TTR V122I variant, earlier screening with echocardiography may inform use of novel therapies targeting TTR amyloid deposition and intensification of risk factor modification to prevent or postpone heart failure, and this option should be studied.

Importance  The variant V122I is commonly enriched in the transthyretin (TTR) gene in individuals of African ancestry and associated with greater risk of heart failure (HF) in older adulthood, after age 65 years. Prevention of HF may be most effective earlier in life, but whether screening with echocardiography can identify subclinical cardiac abnormalities during middle age to risk-stratify individuals appears to be unknown.

Objective  To examine the association between the V122I TTR variant and cardiac structure and function during middle age in those without prevalent HF.

Design, Setting, and Participants  This serial cross-sectional study of 875 Black participants in the Coronary Artery Risk Development in Young Adults (CARDIA) cohort was conducted at 4 urban sites across the US. Recruiting was completed in 1985-1986, and follow-up examinations occurred 25 and 30 years later. A subset of Black adults from the CARDIA cohort who underwent TTR genotyping was included. Data analysis was completed from January 2020 to October 2020.

Exposures  The V122I TTR genotype.

Main Outcomes and Measures  Echocardiographic left ventricular (LV) circumferential and longitudinal systolic strain and LV structure, measured at years 25 and 30 of follow-up. The analyses were adjusted for age, sex, echocardiography quality, genetic ancestry, and field center.

Results  Among the 875 Black adults (mean [SD] age, 49.4 [3.8] years at year 25; 543 women [62.1%]), there were 31 individuals who were heterozygous and 1 who was homozygous for the V122I TTR variant. Of the adults who had an echocardiogram at year 25, rates of hypertension (312 [46%]), diabetes (102 [15%]), and current smoking (128 [19%]) were not significantly different between those who did and did not carry V122I TTR. At year 25, there was no difference in LV circumferential strain, longitudinal strain, or LV structure between those who did vs did not carry V122I TTR. At year 30, those who carried V122I TTR had significantly lower absolute LV circumferential strain (mean [SD], 12.4 [4.2] percentage units) compared with those who did not carry the variant (mean [SD], 14.5 [3.7] percentage units). Those who carried V122I TTR also had significantly higher LV mass index values (mean [SD], 97.5 [34.1] g/m²) compared with those who did not (mean [SD], 83.7 [22.6] g/m²) at year 30.

Conclusions and Relevance  Carrier status for the V122I TTR variant is associated with subclinical cardiac abnormalities in middle age (worse LV systolic function and higher LV mass) that have been associated with increased risk of incident HF. Midlife screening of individuals who carry V122I TTR with echocardiography may prognosticate risk of symptomatic HF and inform prevention strategies.