Brisbane pathologists have criticised updated NHF/CSANZ guidelines on the use of high sensitivity cardiac troponin in managing suspected acute coronary syndromes, claiming that some of the recommendations are not supported by a high level of evidence, do not follow the universal definition of myocardial infarction, and use terms that may be ambiguous.
Dr Jacobus Ungerer and colleagues from the Royal Brisbane and Women’s Hospital, in a letter to Heart Lung and Circulation, said the guidelines were premature and had the potential to cause confusion in the use and interpretation of troponin measurements.
They said the recommendation to use high sensitivity troponin, when available, in preference to conventional assays failed to define the terms ‘high sensitivity’ and ‘conventional’.
“It may unfairly advantage a specific troponin assay supplier that markets it under the trade name ‘high sensitivity troponin T’,” they said.
The term ‘conventional’ implied that other assays were inferior, even though they were likely to provide similar diagnostic accuracy.
In addition, Dr Ungerer and colleagues queried whether a positive result should be defined by a troponin level greater than the 99th percentile, or greater than or equal to the 99th percentile, and said the definition of a 50% increase between serial measurements as ‘significant’ was based only on consensus opinion.
In reply Professor Derek Chew, lead author of the 2011 update to the guidelines, acknowledged the need for continued revision as new evidence became available.
He stressed that the recommendations aimed to help clinicians integrate more sensitive troponin assays into protocols for managing the hundreds of thousands of Australian patients who presented to emergency services with undifferentiated chest pain every year. In those circumstances, troponin assays were used most commonly to rule out infarction rather than make a diagnosis.
There was emerging data that even low levels of absolute change in troponin may indicate, but not necessarily confirm, the presence of an evolving MI.
Heart Lung Circulation doi:10.1016/j.hlc.2011.10.016