Consideration of a New Definition of Clinically Relevant Myocardial Infarction After Coronary Revascularization An Expert Consensus Document From the Society for Cardiovascular Angiography and Interventions (SCAI)

Numerous definitions have been proposed for the diagnosis of myocardial infarction (MI) after coronary revascularization. The universal definition for MI designates post procedural biomarker thresholds for defining percutaneous coronary intervention (PCI)-related MI (type 4a) and coronary artery bypass grafting (CABG)-related MI (type 5), which are of uncertain prognostic importance. In addition, for both the MI types, cTn is recommended as the biomarker of choice, the prognostic significance of which is less well validated than CK-MB. Widespread adoption of a MI definition not clearly linked to subsequent adverse events such as mortality or heart failure may have serious consequences for the appropriate assessment of devices and therapies, may affect clinical care pathways, and may result in misinterpretation of physician competence. Rather than using an MI definition sensitive for small degrees of myonecrosis (the occurrence of which, based on contemporary large-scale studies, are unlikely to have important clinical consequences), it is instead recommended that a threshold level of biomarker elevation which has been strongly linked to subsequent adverse events in clinical studies be used to define a "clinically relevant MI." The present document introduces a new definition for "clinically relevant MI" after coronary revascularization (PCI or CABG), which is applicable for use in clinical trials, patient care, and quality outcomes assessment. Numerous definitions for the diagnosis of MI after coronary revascularization are in use (1). A standardized MI definition would provide uniformity for comparing clinical trial results, for assessing patient outcomes and for guiding quality improvement initiatives. In 2007, a "universal definition" for MI following coronary revascularization was proposed (2) and recently revised in 2012 (3). In this document, a PCI-related MI (type 4a) was defined as an increase in cTn to >5Â the 99th percentile of the URL during the first 48 h following PCI (in patients with normal baseline cTn concentrations), plus either: 1) evidence of prolonged ischemia as demonstrated by prolonged chest pain; or 2) ischemic ST-segment changes or new pathological Q waves; or 3) angiographic evidence of a flow limiting complication; or 4) imaging evidence of new loss of viable myocardium or new regional wall motion abnormality. MI associated with CABG (type 5) was defined as an increase in cTn to >10Â the 99th percentile URL during the first 48 h following CABG (in patients with normal baseline cTn concentrations), plus either: 1) new pathological Q waves or new LBBB; or 2) angiographically documente