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The effect of intravenously administered magnesium on platelet function in patients after cardiac surgery
1Department of Anesthesiology, University of Heidelberg, Germany. ANDREvGRIES@med.uni-heidelberg.de
Insights
Magnesium administration after cardiac surgery was found to inhibit platelet function, potentially impacting bleeding risk. Careful consideration of magnesium dosage is advised for patients with pre-existing bleeding issues.
Area of Science:
- Cardiovascular Surgery
- Hematology
- Pharmacology
Background:
- Magnesium is frequently used post-cardiac surgery to manage arrhythmias.
- However, magnesium is known to affect platelet function.
Purpose of the Study:
- To investigate the impact of magnesium on platelet function in patients following cardiac surgery.
- To assess magnesium's effects on bleeding time, platelet aggregation, and specific platelet activation markers.
Main Methods:
- A randomized, blinded, placebo-controlled study was conducted on patients after coronary revascularization.
- Platelet function was evaluated using bleeding time, platelet aggregation assays, and flow cytometry before and after magnesium infusion.
- In vitro experiments assessed magnesium's dose-dependent effects on platelet-rich plasma.
Main Results:
- Magnesium significantly prolonged bleeding time and inhibited ADP- and collagen-induced platelet aggregation.
- It also reduced platelet P-selectin expression and fibrinogen binding to glycoprotein IIb/IIIa receptors.
- In vitro, magnesium demonstrated dose-dependent inhibition of platelet aggregation and activation markers.
Conclusions:
- Intravenous magnesium administered post-cardiac surgery inhibits platelet function both in vitro and in vivo.
- The antithrombotic potential of magnesium should be weighed against the risk of bleeding, especially in patients with compromised platelet function.
Unlabelled:
After cardiac surgery, magnesium is often administered for prophylaxis and treatment of cardiac arrhythmias. Magnesium, however, inhibits platelet function in vitro and in healthy volunteers. We performed a randomized, blinded, and placebo-controlled study to investigate the effect of magnesium on platelet function in patients after cardiac surgery. We studied patients who underwent uneventful coronary revascularization with cardiopulmonary bypass on the first postoperative day. Before and after an infusion of either 5.4 mmol magnesium (n = 19) or saline (n = 20), platelet function was investigated by means of in vitro bleeding time, platelet aggregation, and flow-cytometric assays. In addition, to investigate platelet function in vitro, 1, 5, and 10 mM magnesium were added to platelet-rich plasma before and 24 h after surgery in 30 patients. Compared with the control group, magnesium prolonged the in vitro bleeding time (22%) and inhibited ADP- and collagen-induced platelet aggregation (13% and 17%), platelet P-selectin expression (18%), and the binding of fibrinogen to the platelet glycoprotein IIb/IIIa receptor (10%). Magnesium also led to significant dose-dependent inhibition of platelet aggregation (19%), P-selectin expression (14%), and fibrinogen binding (11%) before and after surgery in vitro. Although the antithrombotic effect of magnesium may be beneficial in patients after coronary revascularization, large-dose magnesium therapy should be carefully considered in patients with impaired platelet function and co-existing bleeding disorders.
Implications:
In a randomized, blinded, placebo-controlled study of patients 24 h after coronary artery bypass grafting, IV administered magnesium inhibited platelet function in vitro and in vivo.