Coumatetralyl rodenticide induced pericardial effusion — A comment

Dear Sir,

I read with interest the article by Park et al “Successful therapy of coumatetralyl rodenticide induced pericardial effusion with pericardiocentesis in a dog” (Can Vet J 2011;52:165–168). The authors measured cardiac troponin I (cTnI) levels in their patient, and reported a very elevated value (5.42 ng/mL; reference range: 0.0 to 0.7 ng/mL). In the discussion they stated that “Our data were similar to the values obtained with idiopathic pericardial effusion,” and referenced a paper (1) to corroborate this statement. In the reference alluded to, patients with idiopathic pericardial effusion had a mean cTnI value of 0.05 ng/mL (reference range: 0.03 to 0.09 ng/mL), while dogs with effusion due to cardiac hemangiosarcoma had much higher cTnI levels (mean 2.77 ng/mL, reference range: 0.09 to 47.18 ng/mL). The reported patient’s cTnI levels would in fact place it within the referenced study’s hemangiosarcoma group and not in the idiopathic pericardial effusion group. A more recent study (2) (likely published well after Dr. Park’s paper was submitted for publication) also evaluated cTnI in patients with pericardial effusions due to various causes, and also found much higher cTnI values in patients with cardiac hemangiosarcoma (mean 10.7 ng/mL, reference range: 0 to 101.0 ng/mL) than in dogs with idiopathic pericardial effusion (mean 0.1 ng/mL, reference range: 0 to 0.2 ng/mL). This study found measurement of cTnI to be 81% sensitive and 100% specific for the diagnosis of pericardial effusion due to cardiac hemangiosarcoma. Dr. Park’s patient (cTn1 value 5.42 ng/mL) would have fallen within the expected range of patient’s with bleeding cardiac hemangiosacoma in both of these papers, and would have been misdiagnosed as such. I am therefore confused as to the author’s interpretation that their patient’s cTnI value supported idiopathic pericardial effusion.