The things nobody told you about troponin
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Hello. Well, its a huge privilege to kick off this session on the Heart Under Stress and a huge honour that weve got the privilege of having such great people as Edd, Nick and Paul here to join us. Weve really got all aspects covered from Emergency Medicine to Cardiology to Clinical Chemistry with an interactive panel discussion at the end so I hope youll get a lot from it.
Today Im going to speak about the things nobody told you about troponin and I promise not to scare you quite so much as this slide suggests.1
What you dont knowWhat difference does the assay make?Why does hs-troponin allow earlier rule out?
Patient arrivesin the ED: T0
Blood taken30-45 minECG10 minTriage15 min
3h test3h 30 - 3h 45Result 12h 30
Result 2:5h 30 - 5h 454h
Why a 3h Test Doesnt Reduce Admissions
The best study
10ng/L4th Generation troponin T
One of the great things about a high sensitivity assay is that it can detect troponin concentrations in normal healthy individuals, much better than previous generations of troponin assay.
But - at the moment - we don't use that information clinically. Either a patient has a concentration above the 99th percentile - in which case we're concerned - or they don't. It doesn't matter what the level is below the 99th percentile.
But think about all of the diagnostic information we might lose in doing that. The lower you set the cut off for a test, the higher the sensitivity and the negative predictive value. So, if we want a good rule out test with the least possible chance of false negative diagnoses, then we should set the cut off as low as possible - and we could choose the limit of blank - 3ng/L - or the limit of e
95% CI 96.7 - 99.9%95% CI 98.5 - 100.0%
ONE-HOUR RULE OUT1,282 patients0h 4ng/L14.4% ruled inPPV 77.2%Others22.2% patients22.5% had AMISensitivity 96.7%Mueller et al, ESC 2014
Limitations to current strategies: 6h after symptom onset insufficient; 3h rule out has important caveats & surprisingly little evidence too