Coronary artery disease and cardiovascular outcomes in patients with type 2 myocardial infarction

Abstract Purpose To evaluate the association of coronary artery disease with recurrent myocardial infarction and death in consecutive patients with type 2 myocardial infarction. Background Type 2 myocardial infarction occurs due to an imbalance in myocardial oxygen supply or an unmet need in myocardial oxygen demand, without atherothrombosis. It often occurs in the context of another acute illness resulting in tachyarrhythmia, hypoxaemia or hypotension and is responsible for around one in four myocardial infarction events. Patients with type 2 myocardial infarction are at equivalent risk of future cardiovascular events to those with type 1 myocardial infarction, with a six-fold increased risk of recurrent type 2 myocardial infarction events at one year. Whether underlying coronary artery disease is associated with future cardiovascular events and could be a therapeutic target in type 2 myocardial infarction is uncertain. Methods In a secondary analysis of a multi-centre randomised controlled trial implementing a high-sensitivity cardiac troponin assay in 48,282 consecutive patients with suspected acute coronary syndrome, the diagnosis of myocardial infarction was adjudicated according to the Fourth Universal Definition. The primary outcome of any myocardial infarction or death at five years was compared in those with an index diagnosis of type 1 myocardial infarction, and in type 2 myocardial infarction stratified according to presence or absence of coronary artery disease, defined as those with or without a history of prior myocardial infarction, percutaneous coronary intervention or coronary artery bypass grafting. Results The primary outcome occurred in 43.2% (2,154/4,981) of patients with type 1 myocardial infarction, 47.8% (319/667) of patients with type 2 myocardial infarction without coronary disease and 71.4% (324/454) of patients with type 2 myocardial infarction and known coronary artery disease. Compared to patients with type 1 myocardial infarction, patients with type 2 myocardial infarction and coronary artery disease were older (78 versus 71 years), and more likely to be male (46% versus 43%) or to have a diagnosis of diabetes mellitus (27% versus 4%), heart failure (43% versus 15%) or cerebrovascular disease (18% versus 8%). At five years, patients with type 2 myocardial infarction and known coronary artery disease were at highest risk of recurrent myocardial infarction or death (Hazard Ratio HR 2.01, 95%CI 1.80-2.27, P0.001, Figure) which persisted after adjustment for co-variates (adjusted HR 1.26, 95%CI 1.12-1.42, P0.001). Conclusion The presence of coronary artery disease is strongly associated with future cardiovascular risk in patients with type 2 myocardial infarction, but at present these patients are not routinely investigated nor treated. Prospective clinical trials are required to define the role of systematic coronary imaging, revascularisation and secondary prevention in this population.Figure 1