Elevated eosinophil counts associated with cardiovascular disease

Key takeaways:

• The study comprised 264,590 patients whose eosinophil levels were measured.
• There were no significant changes in blood pressure following anti-IL-5 therapy, which depletes eosinophils.

SAN DIEGO — Patients with higher eosinophil counts experienced more cardiovascular disease, according to a poster presented at the 2025 American Academy of Allergy, Asthma & Immunology/World Allergy Organization Joint Congress.

“Eosinophils have a lot of roles in the body. They have roles in immunity. They have roles in inflammatory responses and allergic responses,” Victor Y. Chen, MD, second-year internal medicine resident in the department of medicine at the University of Wisconsin-Madison, told Healio.

“And there’s been some emerging and also conflicting evidence in both the preclinical and clinical spaces that they are involved in cardiovascular disease,” he continued. “This is what we wanted to investigate.”

The researchers retrospectively analyzed the electronic health records of 264,590 patients who had their eosinophil counts measured at the University of Wisconsin between 2019 and 2023, stratifying them based on counts of at least 300 cells/µL or lower than 300 cells/µL.

“The elevated absolute eosinophil count group demonstrates a pretty predictably elevated rate of those diseases compared to the lower eosinophil count group,” Chen said.

Hypertension rates included 23% for those with eosinophil counts of 300 cells/µL and higher and 22.2% for those with counts below 300 cells/µL (P < .001).

Coronary heart disease rates included 9.5% for those with eosinophil counts of 300 cells/µL and higher and 8.3% for those with eosinophil counts below 300 cells/µL (P < .001).

Rates of stroke included 2.7% for those with counts of 300 cells/µL and higher and 2.5% for those with counts below 300 cells/µL (P < .001).

Also, the researchers analyzed blood pressure measurements for 85 patients (40% male; average age, 63.6 years) who used anti-IL-5 therapy both during the year before they began this treatment and during the year after it started.

Therapies included benralizumab (Fasenra, AstraZeneca), mepolizumab (Nucala, GSK) and reslizumab (Cinqair, Teva Pharmaceuticals).

“These deplete peripheral eosinophils, so therefore they may have some impact on cardiovascular outcomes,” Chen said. “Specifically in our case, we were looking to see if it would impact blood pressure readings pre- and post-treatment.”

Before treatment, systolic blood pressure averaged 128.6 mmHg and diastolic blood pressure averaged 75.4 mmHg.

“We did not observe any significant difference between the pre- and post-treatment blood pressures,” Chen said.

These findings indicate an association between higher eosinophil counts and cardiovascular disease that is in line with previous data, Chen said, although he cautioned that the study did not use any age restrictions or controls for any specific variables.

“If we control things a bit more, stratify things a bit more — for example, selecting patients older than age 30, patients who actually would have cardiovascular disease — we would probably see a bigger difference,” Chen said.

Also, Chen attributed the lack of difference in blood pressure measurements before and after treatment to the relatively small sample size of 85 patients, adding that the patients in the sample had well controlled blood pressure at baseline.

“We just didn’t see a big impact with the baseline blood pressures already being within a good goal range,” he said.

Additionally, some patients only had three or four blood pressure readings during that timeframe, Chen said.

“The number of blood pressure readings might also have been inadequate to get good power to observe a difference if there is one,” he said.

Next, Chen said that he and his colleagues will investigate the impact of anti-IL-5 therapy on cardiovascular outcomes in a retrospective cohort, monitoring patients with elevated eosinophil counts over 10 years to see if they develop cardiovascular disease.

Chen also advised providers to keep cardiovascular disease in mind when treating patients with higher eosinophil counts.

“As allergy/immunologists, a lot of our patients have elevated eosinophils for other reasons, like allergic asthma or allergic diseases,” he said. “That might put them at higher risk for development of these cardiovascular diseases, which is going to circle back and impact their health in other ways too.”

For more information:

Victor Y. Chen, MD, can be reached at allergy@healio.com.