Can eye pupil size predict death and hospital readmission in patients with heart failure? Study says it can
Globally, an estimated 26 million people live currently with heart failure, a life-threatening condition in which the heart is unable to pump enough blood to meet the body's needs. Finding better ways to pinpoint which patients are more likely to be readmitted or die with this condition is crucial, and researchers have now found that a person's pupil size predicts death and hospital readmission in people with heart failure.
“Our 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 outlook,” says study author Dr Kohei Nozaki of Kitasato University Hospital, Kanagawa, Japan. The findings have been published in ESC Heart Failure, a journal of the European Society of Cardiology (ESC).
According to the authors, heart failure is one of the leading causes of death around the world, and symptoms in people 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, they add. “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,” the team writes.
Pupil area is another way to evaluate autonomic function and has been used in patients with Parkinson’s disease and diabetes, say researchers. Accordingly, they examined whether the pupil area could predict prognosis in patients with heart failure.
The study was conducted in 870 patients hospitalized for acute heart failure from 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 tested at a standard time (between 9 am and 12 pm) since the autonomic system is affected by the time of day.
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 (16.6 mm2). 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.
The authors found that “photograph of the eyes provides forecast of longevity” in heart failure patients. 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. Over a median follow-up of 1.9 years, 131 patients died due to heart failure: 87 out of 434 or 20% in the small pupil area group and 44 out of 436 or 10.1% in the large pupil area group. Cardiovascular deaths occurred in 90 patients. Patients with small pupil area had significantly higher rates (61 or 14.1%) of cardiovascular death versus 29 or 6.7% in the large pupil area group.
The analysis also shows that 328 were rehospitalized because of heart failure. This includes 205 (47.2%) in the small pupil area group and 123 (28.2%) in the large pupil area group. Large pupil area was consistently linked with favorable survival regardless of age, sex, and the presence of either normal heart rhythm or atrial fibrillation (irregular and often rapid heart rate). “After adjustment for several pre‐existing prognostic factors, including Seattle Heart Failure Score (SHFS), pupil area was shown to be independently associated with all‐cause mortality (hazard ratio: 0.72) and readmission due to heart failure (hazard ratio: 0.82),” the authors conclude. The research team, however, emphasizes that pupil area cannot be used in patients with severe retinopathy or other eye diseases.
“Pupil area can be obtained rapidly, easily, and non-invasively. Our 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 (for example, less than 16.6 mm2) could be prioritized for cardiac rehabilitation with physical activity, which has been reported to improve autonomic function,” recommends Dr Nozaki.