Optical Coherence Tomography-Angiography Metrics in Patients with Atrial Fibrillation and Cerebral Microbleeds

BackgroundPresence of cerebral microbleeds (CMB) on MRI brain, increases risk of intracerebral haemorrhage in patients with atrial fibrillation (AF) who require anticoagulation. The retina shares similar embryological and pathological properties with cerebral vessels. Studying changes in retinal vasculature at capillary level associated with presence of CMB may provide complementary prognostic information to assess risk of anticoagulant-related intracerebral hemorrhage. We aimed to investigate changes in the retinal capillary network associated with presence of CMB in patients with AF using Optical Coherence Tomography-Angiography (OCT-A). MethodsPatients with AF were prospectively recruited to undergo both OCT-A and MRI brain. OCT-A metrics of the superficial capillary plexus (SCP) and deep capillary plexus (DCP) at macular region, along with the radial peripapillary capillary network at disc center were measured quantitatively by an automated image analysis program. Multivariable logistic regression and quasi-poisson regression were performed to investigate the association of OCT-A metrics with presence and burden of CMBs respectively. Significant OCT-A metrics were compared between patients with AF and healthy control subjects. ResultsAmong 99 patients with AF, 29 patients had CMB. A larger foveal avascular zone (FAZ) in SCP, also higher vessel diameter index (VDI) across SCP, DCP and disc center were significantly associated with presence and burden of CMB, after adjusting for age, diabetes mellitus, white matter hyperintensities ratio, image quality index, age, duration between OCT-A and MRI. A lower vessel density in SCP was associated with presence but not burden of CMB. Compared with healthy control, FAZ and VDI across SCP, DCP and disc area remained consistently different between patients with AF and control group. ConclusionsThis pilot study provides preliminary data supporting potential role of OCT-A to assist risk-stratification of bleeding-prone microangiopathy for patients with AF who require anticoagulation. Further studies with larger sample size and different ethnic groups are needed.