Appropriate ischemic criteria for type 4a myocardial infarction: insights from the ALPHEUS trial

Abstract

Abstract Background Different troponin thresholds have been proposed to define periprocedural myocardial injury based on post percutaneous coronary intervention (PCI) troponin increase only, whereas the definition of type 4a myocardial infarction (MI) needs the association of post procedural troponin and one ischemic criterion. These criteria which evolved from the 3rd to the 4th Universal Definition of Myocardial Infarction (UDMI) are frequently under-reported in studies on periprocedural MI. Purpose We aimed to describe rates of type 4a MI additional diagnostic criteria among the ranges of post PCI troponin elevation in the randomized ALPHEUS trial which compared ticagrelor to clopidogrel in high-risk elective PCI patients. Methods 1698 patients with normal pre-PCI troponin values and centralized core laboratory angiogram analyzes were divided into 4 groups according to maximal post PCI troponin elevations (≤ 1x upper reference limit (URL) for group 1; > 1xURL and ≤ 5xURL for group 2; > 5xURL and < 35xURL for group 3 and ≥ 35xURL for group 4). The type 4a MI additional criteria (ischaemic imaging changes, ischaemic ECG changes, chest pain and angiographic complications) as defined by the 3rd and 4th UDMI were reported and the different angiographic complications were detailed for each group. Results The most prevalent additional ischemic criterion was the presence of angiographic complications detected by the core laboratory. The rate of angiographic complications increased in a stepwise manner with higher post PCI troponin elevation (Figure). Interestingly, we found a similar rate of angiographic complications in patients without any increase in post PCI troponin and troponin elevations below the 5xURL threshold (8.4% and 9.9% respectively). Most angiographic complications were related to transient main branch dissection and/or thrombosis, and transient or permanent side branch occlusions (Table). ECG changes and chest pain ischemic criteria also increased in a stepwise manner and were rarely found below the 5-fold threshold increase, although they might be underreported. Conclusion When using a core laboratory, angiographic complications are found even in patients with no or minor troponin elevation. Above the 5 xURL threshold the rates of angiographic complications are 2 to 3-fold more frequent, and ECG changes and chest pain ischaemic criteria are likely to be present. Our findings support the use of angiographic core laboratory in clinical trial using periprocedural MI as an endpoint; similarly, chest pain -which disappeared from the 4th UDMI- should be reconsidered as a diagnostic ischemic criterion.