Signal Strength Variation Explains Apparent Exercise-associated Vessel Density Change on Optical Coherence Tomography Angiography in Heart Failure

Background and Objective: Retinal vessel density (VD) on optical coherence tomography angiography (OCTA) has been proposed as a biomarker in heart failure with preserved ejection fraction (HFpEF). This study evaluated VD change after exercise in HF-pEF, accounting for signal strength. Patients and Methods: Patients with HFpEF underwent 3 × 3-mm OCTA before and after a 6-minute walk test. Change in parafoveal VD in superficial (SCP) and deep (DCP) capillary plexuses was modeled with and without adjustment for signal strength index (SSI) and between New York Heart Association (NYHA) functional classes. Results: Among 34 eyes (20 subjects), unadjusted DCP VD increased after exercise (1.27; 95% CI, 0.31 to 2.24; P = .010), more so in NYHA class III than I or II (difference, 2.39; 95% CI, 0.86 to 3.91; P = .002). SSI adjustment attenuated estimates to nonsignificance (overall, 0.48; 95% CI, −0.23 to 1.19; P = .19; NYHA difference, 0.75; 95% CI, −0.65 to 2.16; P = .29). SCP changes were nonsignificant. Conclusion: Postexercise VD changes in HFpEF were largely explainable by signal strength changes. OCTA analyses should adjust for signal strength to distinguish measurement artifact from true vascular differences.