FOTO-TIA: Focus on the Eye May Discriminate TIA, Stroke vs Mimics

LOS ANGELES — The retinal microvasculature can help differentiate mild stroke and transient ischemic attack (TIA) from a mimic presentation, helping physicians triage patients and initiate appropriate management, new evidence suggests.

Any retinal microvascular finding increased the likelihood of having experienced a cerebrovascular event by almost 16% in a large, prospective study.

"Retinal microvascular findings assessed by nonmydriatic ocular fundus photographs during the evaluation of suspected TIAs are an independent factor differentiating strokes and TIAs from mimics," lead author Fadi Nahab, MD, said during a late breaking abstract session here at the 2020 International Stroke Conference (ISC).

"Retinal microvascular findings provide a really novel diagnostic test for TIA, which in reality remains a diagnosis based on expert opinion."

A Prospective Look

Previous evidence linked retinal microvascular changes to long-term stroke risk and long-term cardiovascular mortality.

For example, the previous Atherosclerosis Risk in Communities Study (ARIC) showed participants with retinal microvascular changes were more likely to experience stroke or TIA over 6 years.

"This did have the limit of being a retrospective study," said Nahab, medical director of the Stroke Program, Emory University Hospital and Emory University Hospital Midtown and associate professor of neurology and pediatrics at Emory University in Atlanta, Georgia.

In contrast, little evidence supports short-term risk stratification in this population. "We hypothesized that retinal microvascular changes have short-term value in risk stratification of people who present with a transient ischemic attack or stroke symptoms to help differentiate [them from] mimics," he added.

FOTO-TIA is a prospective cohort study of 396 adults admitted to one of three emergency department observation units in Atlanta. Nonmydriatic fundus photographs were obtained as part of an accelerated diagnostic protocol for TIA.

Median age was 57 years, 55% were women, and 64% were black. All participants had a National Institutes of Health Stroke Scale score of 3 or less.

A stroke neurologist masked to the identities of the retinal photos assessed whether each patient's presentation represented a cerebrovascular event. This physician judged presence of a TIA or stroke dichotomously (yes/no) and rated the probability of a cerebrovascular event on a 10 cm visual analog scale.

Retinal Results

A total 34 participants or 9% had retinal microvascular findings.

Interpretation of fundus photographs showed 40% of this group had retinal hemorrhages, 32% had cotton wool spots, and 13% had microaneurysms. In addition, 9% had focal arterial narrowing, 6% had retinal occlusions, and 4% featured a retinal embolism.

Any retinal microvascular finding increased the cerebrovascular probability assessment by 15.6% (95% confidence interval [CI], 4.2% - 27.1%; P = .008). This analysis was adjusted for ABCD² score and MRI diffusion weight imaging (DWI) positivity.

Excluding patients with a positive DWI lesion — in other words, those with a definite stroke — any retinal microvascular finding increased the cerebrovascular event probability assessment by 21.8% (95% CI, 6.1% - 37.5%; P = .007). This analysis was adjusted for individual components of the ABCD² assessment tool.

Based on the vascular neurologist's yes or no judgement, 42% of patients had experienced a mild stroke or TIA.

Compared with direct ophthalmoscopy, nonmydriatic fundus photography is "tremendously better" in terms of visualizing the retina, Nahab said. The assessment can be done without ophthalmic experts, he added, and artificial intelligence could further enhance results in future.

"The main intent moving forward is to use AI to provide automated readings of these fundus photographs as a means of providing these results in real-time to ED physicians to better prioritize patients," he said.

"AI will be the key. This is not science fiction anymore," study co-author Valérie Biousse, MD, professor of neuro-ophthalmology and neurology at Emory University School of Medicine said at the conference.

"AI software [for this indication] is being developed within the next year, maybe sooner," she added.

A Lot of Potential

"I think it has a lot of potential," session co-moderator Carolyn Cronin, MD, PhD, assistant professor of neurology at University of Maryland Medical System in Baltimore, Maryland, told Medscape Medical News when asked to comment on the findings.

Cronin said she is looking forward to artificial intelligence expediting the process, "because the speed of interpretation is the limiting factor right now."

During the Q&A, session, co-moderator Amytis Towfighi, MD, associate professor of neurology at the Keck School of Medicine, University of Southern California in Los Angeles, asked Nahab if he factored in a history of hypertension, "which can be a main driver of these retinal changes."

"We haven't looked at that yet, but it is part of a planned analysis," he responded.

A meeting attendee commented that "we already know retinal fundus photography is a good predictor, is this helpful for any differential treatment?"

"That is a great question," Nahab responded. "The biggest challenge, even from our data, is that in the era of accelerated diagnostic protocol . . . the recurrent stroke rates are very low. Trying to identify a difference from treatment will require a very, very large study sample."

The National Institutes of Health funded the study. Nahab, Biousse, Cronin, and Towfighi have disclosed no relevant financial relationships.

International Stroke Conference (ISC) 2020: Late-breaking abstract 6. Presented February 20, 2020.

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