Troponin testing for chest pain in primary healthcare: a New Zealand audit

Serum troponin is a widely used biomarker for the diagnosis of myocardial infarction (MI). The aim of this audit was to document the actual clinical circumstances when serum troponin tests are used to assess chest pain in primary healthcare.

We undertook an audit of general practitioner (GP) serum troponin requests made to community laboratories in the Wellington region over a 5-week period in 2004.

433 tests were ordered by 201 GPs and 10 tests were positive. We faxed 396 questionnaires to identifiable GPs requesting the tests and received 292 replies (74%). The time between initial onset of symptoms and troponin testing was biphasically distributed with peaks at 7-12 hours and 3.5 days. An ECG was performed in less than 50% of the cases. The GP's estimate of the likelihood of their patient's symptoms being due to MI was strongly influenced by both positive and negative test results. Patients were referred acutely to hospital on less than 5% of occasions.

GPs used troponin testing mostly for late presentations some days after chest pain, to 'rule-out' MI. When used acutely, referral for admission occasionally awaited the troponin test result.