A controlled trial found that diclofenac treatment had no effect on post-surgical pericardial effusions or cardiac tamponade.

 Pericardial effusions are common after cardiac surgery and while they are usually asymptomatic a proportion will progress to cardiac tamponade. Larger effusions are more likely to progress in this way: NSAIDs are widely used in an attempt to limit the size of effusions, despite a lack of clinical trial evidence for efficacy. As patients who have recently had cardiac surgery are fragile and NSAIDs may have significant adverse effects, this study was carried out to determine the drugs’ actual efficacy in this situation. Participants were adults who had recently undergone cardiac surgery and were admitted to one of five French cardiac rehabilitation centres with a pericardial effusion. They were randomised to receive diclofenac 50mg or matching placebo twice daily; all patients received peptic ulcer prophylaxis, and low-dose aspirin or oral anticoagulants were given if clinically appropriate. Primary outcome was change in effusion grade from baseline after 14 days of treatment.

 Over 5,000 patients were screened on admission and 262 of these were potentially eligible; 66 were excluded (most due to lack of consent) to leave 196 patients who were randomised to treatment. The majority completed the full course of treatment.

 At 14 days, there was no significant difference between the diclofenac and placebo groups for the primary outcome. At baseline, the mean effusion grade was 2.58 (SD, 0.73) for the placebo group and 2.75 (SD, 0.81) for the diclofenac group, and both groups had similar mean decreases from baseline after treatment (−1.08 grades [SD, 1.20] for placebo vs. −1.36 (SD, 1.25) for diclofenac). The mean difference between groups was −0.28 grade (95% CI, −0.63 to 0.06 grade; P = 0.105). There were 20 cases of late cardiac tamponade overall, 11 in the placebo group and 9 in the diclofenac group (p=0.64).

 The authors conclude on the basis of their results that diclofenac treatment had no effect on the size of post-surgical pericardial effusion, or on cardiac tamponade rate. They add that inflammation is not the predominant cause of pericardial effusion after cardiac surgery, and that NSAID should no longer be recommended as treatment.

 An accompanying editorial discusses the study. The author discusses the management of post-surgical pericardial effusion, and concurs with the study authors that until there are more data, NSAID should no longer be used in this condition in the absence of clear evidence for inflammation.