Eosinophil count predicts mortality risk following heart procedure

By Ingrid Grasmo

Study findings suggest that eosinophil count predicts mortality risk in patients undergoing percutaneous coronary intervention.

Having a high eosinophil count prior to the procedure initially predicted a reduced mortality risk, but this was no longer the case more than 6 months after the surgery, when mortality risk significantly increased instead.

Chetan Varma (City Hospital, Birmingham, UK) and colleagues say the change in mortality risk over time "suggests a dynamic role for eosinophils in the natural history of coronary artery disease (CAD) patients which has not been previously reported."

They add: "Eosinophil count is a novel biomarker for risk stratification of CAD patients at increased risk of adverse outcomes."

For the 6-year study, the researchers measured preprocedural total and differential white blood cell (WBC) counts among 509 patients, aged an average of 64 years, who were admitted for elective or urgent percutaneous coronary intervention.

Over the first 6 months of follow up, 2.6% of patients died with this percentage increasing to 15.2% at 4.5 years.

Cox regression analysis showed that patients with an eosinophil count in the third tertile (0.34x10⁹ cells/L) were 77% less likely to have an adverse outcome within the first 6 months compared with patients who had a count in the first tertile (0.10x10⁹ cells/L).

However, after the initial 6 months, high eosinophil count was significantly associated with a 2.21-fold increased risk for mortality.

The researchers say the poor outcome observed after 6 months may be a result of thrombus formation as eosinophils infiltrate the site of stent implantation and release a number of mediators, increasing platelet activation and aggregation.

Writing in Thrombosis Research the team concludes: "A possible role for eosinophils in regulation of acute inflammation may be a future potential therapeutic target in CAD."

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