Eyes on amyloidosis: microvascular retinal dysfunction in cardiac amyloidosis

AIMS: Cardiac involvement in systemic amyloidosis is a marker of particularly poor prognosis. Cardiac amyloidosis (CA) is characterized by extracellular amyloid deposits inducing heart failure and symptoms of cardiac microvascular disease. While amyloid deposition is most common in the myocardium but also seen in pericardium and endocardium, atria, and vasculature, the role of (micro‐)vascular dysfunction in CA pathophysiology remains still elusive. Because vascular function is associated with cardiovascular risk and severity of heart failure and represents a potential therapeutic target in CA, the present study investigated retinal vascular function, flow‐mediated dilatation (FMD), and pulse‐wave analysis and velocity (PWA/PWV) in patients with CA. METHODS AND RESULTS: Flicker‐induced arterial dilatation (FIDa) was measured using dynamic retinal vessel analysis additionally to FMD and PWA/PWV. Thirty‐three patients with CA [age 67 years [interquartile range, IQR, 62, 74], 14 with amyloid light‐chain (AL) and 19 with transthyretin (ATTR) amyloidosis] were prospectively included in this cross‐sectional, observational study and 70 healthy individuals (age 53 years [IQR 39, 67]) served as control. Potential confounders were balanced using entropy balancing propensity score analysis [inverse probability weighting (IPW)]. FIDa was reduced in CA patients (1.52 ± 1.73% vs. 3.09 ± 1.96%, P < 0.001, after IPW). While PWV was increased (8.74 ± 2.34 m/s vs. 7.49 ± 1.65 m/s, P = 0.018, after IPW), no difference in FMD was observed. FIDa was significantly associated with prognostic biomarkers of CA [estimated glomerular filtration rate (r = 0.33; P < 0.001), log‐scaled troponin T (r = −0.49; P < 0.001), and N‐terminal pro‐B‐type natriuretic peptide (r = −0.51; P < 0.001)]. CONCLUSIONS: Retinal vascular function is impaired, associated with cardiac and renal biomarkers of CA severity, and may represent a potential therapeutic target in patients with amyloidosis.