Stabilized Infective Endocarditis and Altered Heparin Responsiveness During Cardiopulmonary Bypass

Background: Although active infective endocarditis (IE) is known as a risk factor for decreased heparin responsiveness during cardiopulmonary bypass (CPB), evidence is lacking in patients with stabilized IE. We investigated whether heparin responsiveness was still altered in stabilized IE patients undergoing cardiac surgery in a prospective, controlled trial.

Methods: A total of 16 patients with stabilized IE without signs of active inflammation (IE group) and 48 patients without systemic infection (control group) undergoing valve surgery were included. Heparin responsiveness was assessed using the heparin sensitivity index (HSI), whereas heparin resistance was defined as an activated clotting time (ACT) occurring less than 400 s after the initial heparinization.

Results: Preoperative antithrombin III activity was lower and fibrinogen level was higher in the IE group. ACT after initial heparinization was shorter in the IE group. The HSI was lower and the number of patients with HSI <1.0 was greater in the IE group. Heparin resistance occurred more frequently in the IE group.

Conclusions: Heparin responsiveness during CPB was significantly reduced in the IE group, and it seems to be associated with preoperative hypercoagulability and reduced antithrombin III activity. Therapeutic measures such as the administration of antithrombin III concentrate should be considered in these patients even when they are in a stabilized condition without active inflammation.