In a new study, researchers found pupil size can predict death and hospital readmission in patients with heart failure.
The results suggest that pupil area is a novel way to identify heart patients at elevated risk of death or hospital readmission. This provides an opportunity to intervene and improve the outlook.
The research was conducted by a team at Kitasato University Hospital, Kanagawa, Japan.
Around 26 million people worldwide currently live with heart failure. It is a life-threatening condition in which the heart is unable to pump enough blood to meet the body’s needs.
Symptoms include shortness of breath, swollen limbs and fatigue.
Up to 45% of patients admitted to hospital with heart failure die within one year of admission and the majority die within five years of admission.
Finding better ways to pinpoint which patients are more likely to be readmitted or die is crucial.
One of the causes of worsening heart failure is a disturbed function of the body’s autonomic system, which controls heart rate, digestion, respiration, and so on.
The autonomic function is typically evaluated by measuring changes in heart rate. However, this method is ineffective in patients with a heart rhythm disorder called atrial fibrillation, which is common in those with heart failure.
Pupil area is another way to assess autonomic function and has been used in patients with Parkinson’s disease and diabetes.
This study examined whether the pupil area could predict prognosis in patients with heart failure.
The research was done in 870 patients hospitalized for acute heart failure in 2012 to 2017. The average age was 67 years and 37% were women.
Pupil area was measured in both eyes at least seven days after hospital admission.
For the test, patients put on goggles, waited five minutes for their eyes to adapt to the dark, then photos were taken of the eyes.
Patients were divided into the small pupil area group and large pupil area group according to whether their measurement was below or above the median.
They were then followed-up for all-cause death (the primary endpoint) and readmission due to heart failure (the secondary endpoint). Results of the small and large pupil area groups were compared.
Over a follow-up of 1.9 years, 131 patients died and 328 were re-hospitalized because of heart failure.
Compared to the large pupil area group, patients in the small pupil area group had a significantly poorer survival rate and a significantly higher rate of readmission for heart failure.
The team found patients with a small pupil area had a 28% lower risk of all-cause mortality and an 18% reduced risk of readmission due to heart failure compared to patients with a large pupil area.
Large pupil area was consistently linked with favorable survival regardless of age, sex, and the presence of either normal heart rhythm or atrial fibrillation.
The team says pupil area can be obtained rapidly, easily, and non-invasively.
The study indicates that it could be used in daily clinical practice to predict prognosis in patients with heart failure, including those who also have atrial fibrillation.
Patients with a small pupil area (e.g. less than 16.6 mm2) could be prioritized for cardiac rehabilitation with physical activity, which has been reported to improve autonomic function.
The team noted that the pupil area cannot be used in patients with severe retinopathy or other eye diseases.
One author of the study is Dr. Kohei Nozaki.
The study is published in ESC Heart Failure.
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