Impact of transition to high-sensitivity troponin on investigations after type 2 myocardial infarction: a single centre retrospective cohort study

Abstract Background Optimal investigation and management pathways for type 2 myocardial infarction (T2MI) remain unclear despite advances in diagnostic modalities. Our institution transitioned to using high-sensitivity cardiac troponin (hs-cTn) assays for the diagnosis of myocardial infarction in 2019. We conducted a study to investigate the impact of this change on investigations for patients with T2MI. Purpose The purpose of this study was to examine the impact of the transition to the new hs-cTn assay in directing further imaging and invasive investigations for patients with T2MI at our institution. We hypothesised that this change could lead to an increase in investigations being performed. Methods This retrospective cohort study compared investigation pathways following T2MI using standard-sensitivity cardiac troponin (ss-cTn) assays in 2018 and hs-cTn assays in 2019 at our institution. We identified every troponin result that was elevated in 2018 and 2019. We followed rigorous criteria in retrospectively distinguishing between type 1 myocardial infarction (T1MI) and T2MI using discharge International Classification of Disease codes. We retrieved patient data on serial troponins and diagnostic investigations including transthoracic echocardiography (TTE), stress echocardiography (Stress ECHO), CT coronary angiogram (CTCA), 99mTc-sestamibi myocardial perfusion imaging (MIBI), invasive coronary angiogram, and percutaneous coronary intervention (PCI). We distinguished between inpatient investigations and outpatient investigations within 1 year of discharge date. Results A total of 7547 patient contacts were identified with myocardial infarction. 3589 were diagnosed using ss-cTn assays in 2018, and 3958 were diagnosed using hs-cTn assays in 2019. In 2018, there were 660 T1MI patients and 2929 T2MI patients respectively. In 2019, there were 666 T1MI patients and 3291 T2MI patients respectively. Of all investigations, proportions of stress ECHOs and CTCAs following T2MI significantly increased following the introduction of hs-cTn assays (0.1% vs 0.7%, P