Measuring CK-MB is more clinically relevant for diagnosing MI type 4a, when applying the universal definition. Current troponin thresholds are oversensitive with the arbitrary limit of 3 × 99th percentile failing to discriminate between periprocedural necrosis and MI type 4a. (Myocardial Injury following Coronary Artery bypass Surgery versus Angioplasty: a randomised controlled trial using biochemical markers and cardiovascular magnetic resonance imaging; ISRCTN25699844).

Periprocedural myocardial injury (PMI) is common after percutaneous coronary intervention (PCI). Periprocedural infarction (myocardial infarction type 4a) occurs after at least 10% of PCI procedures and has an impact on long-term prognosis. Measurement of biomarkers to allow assessment of PMI is an important tool for clinical and research purposes and should be routine after every PCI (troponin I or T and CK-MB). The importance of oral and intravenous antiplatelet agents and other drugs which have been proven to reduce PMI is discussed.

Acute sub-clinical circumflex 'injury' following MI ablation is not uncommon. Ablation within the CS, proximity of the circumflex and the CS, and a small distal circumflex were risk factors for 'injury'.