Patient selection for high sensitivity cardiac troponin testing and diagnosis of myocardial infarction: prospective cohort study
Anoop S V Shah1, Yader Sandoval2, Ala Noaman1
1BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh EH16 4SB, UK.
Insights
Patient selection for high sensitivity cardiac troponin testing significantly impacts myocardial infarction diagnosis. Widespread testing without clinical assessment often indicates myocardial injury, not infarction, affecting diagnostic accuracy.
Area of Science:
- Cardiology
- Clinical Diagnostics
Background:
- High sensitivity cardiac troponin (hs-cTn) assays are crucial for diagnosing myocardial infarction (MI).
- Patient selection for hs-cTn testing can vary significantly across healthcare settings.
- The diagnostic utility of hs-cTn depends on the pre-test probability of MI.
Purpose of the Study:
- To evaluate the impact of patient selection strategies on the diagnosis of myocardial infarction using hs-cTn testing.
- To compare the positive predictive value (PPV) of hs-cTn across different clinical settings and patient groups.
- To understand how variations in testing protocols influence MI diagnosis.
Main Methods:
- Prospective study involving 8500 consecutive emergency department patients in the UK and US.
- Measurement of hs-cTn I concentrations in unselected and selected patient cohorts.
- Independent adjudication of myocardial infarction (Type 1 or Type 2) and myocardial injury diagnoses.
Main Results:
- In unselected patients, elevated hs-cTn had a low PPV (11.8%) for Type 1 MI.
- In clinician-selected patients, PPV varied: 59.7% in the UK and 16.4% in the US.
- Higher PPV was observed in selected patients with chest pain, ECG ischemia, and ischemic heart disease history.
Conclusions:
- Widespread or unselected hs-cTn testing often detects myocardial injury rather than MI.
- Patient selection critically influences the PPV of hs-cTn assays.
- Standardized patient selection criteria are essential for accurate MI diagnosis with hs-cTn.
Abstract:
Objective To evaluate how selection of patients for high sensitivity cardiac troponin testing affects the diagnosis of myocardial infarction across different healthcare settings.Design Prospective study of three independent consecutive patient populations presenting to emergency departments.Setting Secondary and tertiary care hospitals in the United Kingdom and United States.Participants High sensitivity cardiac troponin I concentrations were measured in 8500 consecutive patients presenting to emergency departments: unselected patients in the UK (n=1054) and two selected populations of patients in whom troponin testing was requested by the attending clinician in the UK (n=5815) and the US (n=1631). The final diagnosis of type 1 or type 2 myocardial infarction or myocardial injury was independently adjudicated.Main outcome measures Positive predictive value of an elevated cardiac troponin concentration for a diagnosis of type 1 myocardial infarction.Results Cardiac troponin concentrations were elevated in 13.7% (144/1054) of unselected patients, with a prevalence of 1.6% (17/1054) for type 1 myocardial infarction and a positive predictive value of 11.8% (95% confidence interval 7.0% to 18.2%). In selected patients, in whom troponin testing was guided by the attending clinician, the prevalence and positive predictive value were 14.5% (843/5815) and 59.7% (57.0% to 62.2%) in the UK and 4.2% (68/1631) and 16.4% (13.0% to 20.3%) in the US. Across both selected patient populations, the positive predictive value was highest in patients with chest pain, with ischaemia on the electrocardiogram, and with a history of ischaemic heart disease.Conclusions When high sensitivity cardiac troponin testing is performed widely or without previous clinical assessment, elevated troponin concentrations are common and predominantly reflect myocardial injury rather than myocardial infarction. These observations highlight how selection of patients for cardiac troponin testing varies across healthcare settings and markedly influences the positive predictive value for a diagnosis of myocardial infarction.
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