Signal Strength Variation Explains Apparent Exercise-associated Vessel Density Change on Optical Coherence Tomography...

Area of Science:

• Ophthalmology
• Cardiology
• Biomedical Imaging

Background:

• Retinal vessel density (VD) measured by optical coherence tomography angiography (OCTA) is a potential biomarker for heart failure with preserved ejection fraction (HFpEF).
• Exercise-induced changes in VD require careful interpretation, especially considering potential confounding factors.

Purpose of the Study:

• To evaluate changes in retinal vessel density (VD) after exercise in patients with heart failure with preserved ejection fraction (HFpEF).
• To assess the impact of signal strength index (SSI) on the interpretation of VD changes.
• To investigate differences in VD changes across New York Heart Association (NYHA) functional classes.

Main Methods:

• Patients with HFpEF underwent OCTA scans before and after a 6-minute walk test.
• Parafoveal VD was measured in superficial (SCP) and deep (DCP) capillary plexuses.
• VD changes were analyzed with and without adjustment for signal strength index (SSI).

Main Results:

• Unadjusted analysis showed an increase in deep capillary plexus (DCP) VD after exercise, particularly in NYHA class III patients.
• Signal strength index (SSI) adjustment attenuated these findings, rendering the overall and NYHA class-specific VD changes nonsignificant.
• No significant changes were observed in the superficial capillary plexus (SCP).

Conclusions:

• Observed post-exercise VD changes in HFpEF are largely attributable to variations in signal strength, not true physiological alterations.
• OCTA analyses require adjustment for signal strength to differentiate genuine vascular changes from measurement artifacts.
• This highlights the importance of rigorous data processing in OCTA-based biomarker research.