Correspondence |
Pitfalls and problems of relying on serum troponin
Sir,In the differential diagnosis of the co-existence of retrosternal pain and troponinosis,1 it is also worth highlighting acute pericarditis unrelated to myocardial infarction (MI). In a study of 69 patients with acute idiopathic pericarditis, 15 (22%) exceeded the threshold value for MI (1.5 ng/ml), with a mean value of 17 ng/ml.2 According to other studies, electrocardiographic (ECG) stigmata of acute pericarditis may simulate those of uncomplicated MI, increasing the risk of exposure of the patient to inappropriate thrombolysis, and its attendant adverse effects.
For example, instead of the expected diffuse ST segment elevation, patients in whom acute pericarditis is unrelated to myocardial infarction may manifest localized ST segment elevation simulating anteroseptal MI,3 and the ST segment elevation detected in the anterior leads may itself sometimes assume a 'tombstone' configuration simulating MI.4 Neither does absence of the expected reciprocal ST segment depression necessarily differentiate between pericarditis and MI, given the fact that absence of reciprocal ST segment depression may occur in up to 30% of inferior, and 70% of anterior, MIs.5
Accordingly, frontline medical staff need to be re-educated, not only about the pitfalls and problems of relying on serum troponin, but also about the suboptimal specificity of ECG stigmata, which are supposed to differentiate between the two prime candidates for the association of retrosternal pain, troponinosis, and ST segment elevation: namely, MI and pericarditis.
Retired geriatrician
References
1. Burness CE, Beacock D, Channer KS. Pitfalls and problems of relying on serum troponin. Q J Med 2005; 98:365.
2. Bonnefoy E, Godon P, Kirkorian G, et al. Serum cardiac troponin I and ST segment elevation in patients with acute pericarditis. Eur Heart J 2000; 21:832–6.
3. Smith KJ, Theal M, Mulji A. Pericarditis presenting and treated as an acute anteroseptal myocardial infarction. Canad J Cardiol 2001; 17:815–17.
4. Jain A. 'Tombstone' anterior ST segment elevations secondary to acute pericarditis: the role of two-dimensional echocardiograms. Clin Cardiol 1997; 20:404–6.[Medline]
5. Morris F, Brady WJ. ABC of clinical electrocardiography: Acute myocardial infarction—Part 1. Br Med J 2002; 324:831–4.
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