What is the significance of a peak post-procedure high sensitivity troponin (hs-Tn) level above 5 times the 99th percentile upper reference limit (URL) in elective percutaneous coronary intervention (PCI)?

From the Guidelines

A peak post-procedure high sensitivity troponin (hs-Tn) level above 5 times the 99th percentile upper reference limit (URL) following elective percutaneous coronary intervention (PCI) is clinically significant as it meets the diagnostic criteria for a type 4a myocardial infarction, as defined by the Universal Definition of MI 1. This elevation indicates procedural-related myocardial injury that is substantial enough to be classified as a periprocedural MI. The most recent and highest quality study on this topic is from 2019, which provides recommendations for institutions transitioning to high-sensitivity troponin testing, including the use of hs-Tn for detecting periprocedural MI after PCI 1. However, it's worth noting that a more recent study from 2021 suggests that the use of hs-troponins may greatly inflate the absolute rate of procedural MI, and recommends the use of a higher threshold of ≥70 times the 99th percentile of the URL for that hs-troponin assay plus the presence of at least one of the following criteria: (1) TIMI grade 0 to 1 flow in a main epicardial vessel or a side branch >2.0 mm in diameter that had TIMI grade 2 to 3 flow before PCI, (2) new pathological Q waves in ≥2 contiguous leads or new persistent left bundle-branch block, or (3) a new wall motion abnormality related to the procedure 1. Some key points to consider in the management of these patients include:

• The mechanism behind this elevation usually involves distal embolization of plaque material, side branch occlusion, or transient ischemia during balloon inflation.
• Patients with this degree of troponin elevation typically require closer monitoring and may have an increased risk of adverse cardiovascular outcomes, including higher rates of mortality and major adverse cardiac events in the months to years following the procedure.
• While no specific medication regimen is universally mandated solely based on this troponin elevation, these patients should continue standard post-PCI care including dual antiplatelet therapy (typically aspirin 81mg daily indefinitely plus a P2Y12 inhibitor such as clopidogrel 75mg daily, ticagrelor 90mg twice daily, or prasugrel 10mg daily for at least 6-12 months).
• Additionally, these patients may benefit from more intensive secondary prevention measures, including optimal statin therapy, blood pressure control, and closer follow-up to monitor for any clinical deterioration or symptoms.

From the Research

Significance of Peak Post-Procedure High Sensitivity Troponin in Elective PCI

• The significance of a peak post-procedure high sensitivity troponin (hs-Tn) level above 5 times the 99th percentile upper reference limit (URL) in elective percutaneous coronary intervention (PCI) is associated with an increased risk of mortality and major adverse cardiac events (MACE) 2.
• A study found that major myocardial injury defined by post-PCI ≥5 × 99th percentile URL occurred in 18.2% of patients and was associated with a two-fold increase in the adjusted odds of 1-year mortality 2.
• However, another study found that periprocedural troponin elevation after left main PCI was not associated with adverse long-term outcomes, suggesting that the isolated periprocedural troponin elevation may not be clinically significant 3.
• The prognostic value of procedure-related myocardial infarction according to the universal definition of myocardial infarction in saphenous vein graft interventions was found to be associated with an adverse in-hospital course but may not predict long-term outcome 4.
• A three-fold elevation of troponin I after successful elective PCI was independently predictive of MACE, especially the need for early repeat revascularization 5.

Predictors of Post-Procedure Troponin Elevation

• Multivessel PCI, overlapping stenting, predilatation, postdilatation, and longer stent length are associated with periprocedural myocardial injury (PMI) following elective PCI 6.
• Procedural side branch occlusion and thrombus formation are predictors of troponin I elevation after PCI 5.
• Complex angiographic features, such as type C lesions, are more common in patients with procedure-related myocardial infarction 4.