A single centre prospective cohort study addressing the effect of a rule-in/rule-out troponin algorithm on routine clinical practice

Abstract

Aims: In 2015, the European Society of Cardiology introduced new guidelines for the diagnosis of acute coronary syndromes in patients presenting without persistent ST-segment elevation. These guidelines included the use of high-sensitivity troponin assays for 'rule-in' and 'rule-out' of acute myocardial injury at presentation (using a '0 hour' blood test). Whilst these algorithms have been extensively validated in prospective diagnostic studies, the outcome of their implementation in routine clinical practice has not been described. The present study describes the change in the patient journey resulting from implementation of such an algorithm in a busy innercity Emergency Department.

Methods and results: Data were prospectively collected from electronic records at a large Central London hospital over seven months spanning the periods before, during and after the introduction of a new high-sensitivity troponin rapid diagnostic algorithm modelled on the European Society of Cardiology guideline. Over 213 days, 4644 patients had high-sensitivity troponin T measured in the Emergency Department. Of these patients, 40.4% could be 'ruled-out' based on the high-sensitivity troponin T concentration at presentation, whilst 7.6% could be 'ruled-in'. Adoption of the algorithm into clinical practice was associated with a 37.5% increase of repeat high-sensitivity troponin T measurements within 1.5 h for those patients classified as 'intermediate risk' on presentation.

Conclusions: Introduction of a 0 hour 'rule-in' and 'rule-out' algorithm in routine clinical practice enables rapid triage of 48% of patients, and is associated with more rapid repeat testing in intermediate risk patients.

Keywords: High-sensitivity cardiac troponin T; acute coronary syndrome; rule-in/rule-out algorithm.

Conflict of interest statement

Conflict of interest: MS Marber is named as an inventor on a patent held by King’s College London for the detection of cardiac myosin binding protein-C as a biomarker of myocardial injury. The remaining authors have no conflict of interest to report.

Figures

Figure 1.

The high-sensitivity troponin T (hs-cTnT) rapid diagnostic algorithm introduced at St Thomas’ Hospital. ACS: Acute Coronary Syndrome; LBBB: Left Bundle Branch Block; ECG: electrocardiogram; PCI: Percutaneous Coronary Intervention.

Figure 2.

Bar graph summarising the presenting complaint of all patients (n=4644) with a measured high-sensitivity troponin T (hs-cTnT) in the entire study period; frequencies quoted as percentage of the cohort. SOB: Shortness of Breath.

Figure 3.

Graph outlining the distribution of all high-sensitivity troponin T (hs-cTnT) values measured on patients presenting to the Emergency Department during the monitoring period (September 2015–March 2016; n=4644); the following thresholds applied: <5 ng/l ‘rule-out’, 5-50 ng/l ‘observe’, >50 ng/l ‘rule-in’.

Figure 4.

Bar graph summarising the discharge diagnosis of all admitted patients in the monitoring period (September 2015–March 2016; n=1876); frequencies quoted as percentage of the overall number of patients admitted following high-sensitivity troponin T (hs-cTnT) testing. CCF: congestive cardiac failure; GI: gastrointestinal disorder; IHD: ischaemic heart disease; MSK: musculo-skeletal disorder; OAD: obstructive airways disease; PE: pulmonary embolism. ‘Cardiac other’ includes myocarditis, valvular heart, conduction tissue and pericardial disease; ‘Resp other’ includes pleural effusion; GI includes gastro-oesophageal reflux disease, gastroenteritis and symptomatic cholelithiasis; ‘Infection’ includes lobar pneumonia, urinary tract infection and influenza; MSK includes costochondritis, bony fractures and other injuries; ‘Other’ includes sickle-cell anaemia, malignancy and mental health disorder.

Figure 5.

Bar graphs summarising the discharge diagnosis of all admitted patients in the monitoring month with an initial high-sensitivity troponin T (hs-cTnT) level >50 ng/l (n=247); frequencies quoted as percentage. CCF: congestive cardiac failure; GI: gastrointestinal disorder; IHD: ischaemic heart disease; MSK: musculo-skeletal disorder; OAD: obstructive airways disease; PE: pulmonary embolism. ‘Cardiac other’ includes myocarditis, valvular heart, conduction tissue and pericardial disease; ‘Resp other’ includes pleural effusion; GI includes gastro-oesophageal reflux disease, gastroenteritis and symptomatic cholelithiasis; ‘Infection’ includes lobar pneumonia, urinary tract infection and influenza; MSK includes costochondritis, bony fractures and other injuries; ‘Other’ includes sickle-cell anaemia, malignancy and mental health disorder.