Background: Raised plasma levels of endogenous adenosine after cardiac surgery using cardiopulmonary bypass (CPB) have been related to the incidence of postoperative atrial fibrillation (POAF).
Objective: We wished to assess if caffeine, an adenosine receptor antagonist could have a beneficial effect on the incidence of POAF.
Design: A randomised controlled study.
Setting: Single University Hospital.
Patients: One hundred and ten patients scheduled for heart valve surgery with CPB.
Interventions: We randomly assigned patients to receive peri-operative oral caffeine (400 mg every 8 h for 2 days) or placebo. Adenosine plasma concentrations and caffeine pharmacokinetic profile were evaluated in a subgroup of 50 patients.
Main outcome measures: The primary endpoint was the rate of atrial fibrillation during postoperative hospital stay.
Results: The current study was stopped for futility by the data monitoring board after an interim analysis. The incidence of atrial fibrillation was similar in the caffeine and in the placebo group during hospital stay (33 vs. 29%, P = 0.67) and the first 3 postoperative days (18 vs. 15%; P = 0.60). Basal and postoperative adenosine plasma levels were significantly associated with the primary outcome. Adenosine plasma levels were similar in the two treatment groups. Caffeine administration was associated with a higher incidence of postoperative nausea and vomiting (27 vs. 7%, P = 0.005).
Conclusion: Oral caffeine does not prevent POAF after heart valve surgery with CPB but increased the incidence of postoperative nausea and vomiting.
Clinical trial registration: ClinicalTrials.gov, no.: NCT01999829.