Haemopericardium can occur in the setting of trauma. Non-traumatic causes include malignancy, myocardial infarction, dissection of the aorta, and postmyocardial infarction syndrome.1
Excessive anticoagulation is a rare cause and our patient had an unusual presentation.
There are very few published cases concerning cardiac tamponade associated with anticoagulation. Generally, onset of symptoms are gradual—classically dyspnoea, tachycardia, tachypnoea, malaise, abdominal distension, diaphoresis, distorted LFTs, and clotting—with pericardiocentesis as the standard treatment.
cites the case of haemorrhagic pericardial effusion 2 weeks following insertion of a dual chamber pacemaker in a patient on warfarin and amiodarone. The interaction between amiodarone and warfarin was the suggested aetiology.
Granot and Shiner,3
Kamthorn and Marwick,4
and Yu-Cheng et al5
described spontaneous haemopericardium in a patient on warfarin. In all these cases, no evidence of infective, autoimmune or malignant causes was found and warfarin treatment was thought to be the cause.
In our case, excessive anticoagulation might be caused by the interaction between erythromycin and warfarin. Erythromycin inhibits the metabolism and subsequent clearance of warfarin from the body. The activity of warfarin may also be prolonged due to alterations in the intestinal flora and its generation of vitamin K for clotting factor production.
It would be unwise to associate this case entirely with warfarin usage although it was likely to have been a principle contributory factor. First, there was the interaction between warfarin and erythromycin to be considered; secondly, before presentation the patient was diagnosed with a chest infection possibly precipitating the pericarditis. In addition the patient had a longstanding myeloproliferative disorder with dysfunctional platelets. In conclusion, it may be suggested that the aetiology of the haemopericardium was multifactorial.
- Over anticoagulation with warfarin should be strictly avoided as it can lead to potentially serious complications.
- Drug interactions between warfarin and other medications should be considered before any medical prescription. One example is concomitant use of a macrolide with warfarin. Microbial pathogen identification before antibiotic initiation will decrease the prevalence of unnecessary drug interaction risk.
- Internal bleeding, including haemorrhagic cardiac tamponade, should be ruled out in patients on warfarin with unexplained hypotension and excessive anticoagulation.