The prognostic relevance of periprocedural myocardial infarction (PMI) in patients with chronic coronary syndrome undergoing percutaneous coronary intervention (PCI) is still matter of debate, particularly regarding the type (cardiac troponin or creatin kinase-MB) and different thresholds of biomarkers elevation, as the importance of associated ancillary criteria of ischemia or concomitant angiographic complications. There are still uncertainties regarding the value of PMI as event which is prognostically equivalent to spontaneous myocardial infarction or if it simply represents a marker of baseline risk, atherosclerotic burden and procedural complexity. In the present review, we will present the mechanisms and predictors of PMI occurring during PCI and potential treatment strategies to reduce its occurrence. We will also overview all commonly adopted definitions of PMI, which carry different prevalence and prognostic implications in daily practice and clinical trials. Finally, we will discuss the impact of different PMI definitions on the interpretation of trials results, emphasizing the importance of adequate endpoints selection in the planning and interpretation of clinical trials.