Platelet reactivity in overweight and obese patients undergoing cardiac surgery

Abstract

Body mass index (BMI) and specifically overweight and obesity have been associated with an increased platelet reactivity in different series of patients. This information is derived by different laboratory platelet function tests (PFTs) like mean platelet volume (MPV), platelet microparticles, thromboxane B2 metabolites, and others. Point-of-care PFT, which are often used in cardiac surgery, are rarely addressed. The present study aims to verify platelet reactivity using multiple-electrode aggregometry (MEA) as a function of BMI in cardiac surgery patients. One-hundred ninety-eight cardiac surgery patients free from the effects of drugs acting on the P2Y₁₂ receptor and undergoing cardiac surgery received MEA-PFT immediately before surgery. Platelet reactivity was compared between normal weight and overweight–obese subjects. There were 99 underweight/normal (BMI < 25), 60 overweight (BMI ≥ 25) and 39 obese (BMI ≥ 30) patients. Overweight–obese patients did not show higher platelet counts nor a clear platelet hyper-reactivity, when tested with MPV and MEA ADP test. At TRAPtest, the overweight/obese patients had a significantly (P = 0.011) higher platelet reactivity (median 118, interquartile range 106–136) than controls (median 112, interquartile range 101–123) and a higher rate of platelet hyper-reactivity (odds ratio 2.19, 95% confidence interval 1.15–4.16, P = 0.016) in a multivariable model. A minor association was found between the BMI and platelet reactivity at TRAPtest, with a higher degree of activity for increasing BMI. The BMI determines an increased thrombin-dependent platelet reactivity in cardiac surgery patients. Thrombin is extensively formed during cardiac surgery, and this may explain the lower postoperative bleeding observed in obese patients in previous studies.

Keywords:

• Cardiac surgery
• electric impedance aggregometry
• obesity
• platelet function

Acknowledgements

Marco Ranucci received speaker’s honoraria and research grants from Roche Diagnostics. The study was externally supported by Roche Diagnostics, which provided the reagents for the platelet function tests free of charge and an additional Multiplate device for the study period.

Declaration of interest

Roche Diagnostics had no role in analysis and interpretation of data; in writing the report; and in the decision to submit the article for publication.

Additional information

Funding

This study was supported by internal research funds of the IRCCS Policlinico San Donato, a Clinical Research Hospital partially funded by the Italian Ministry of Health.