Coronary microcirculation and peri-procedural myocardial injury during elective percutaneous coronary intervention

BACKGROUND: Coronary microvascular dysfunction before percutaneous coronary intervention (PCI) predicts PCI-related myocardial injury in patients with stable coronary artery disease (CAD). Whether the dynamic changes of the microcirculation during PCI might be associated with the occurrence of procedure-related myocardial injury and infarction is still unclear. We aimed to investigate the impact of pre- and post-PCI microvascular function, evaluated with the index of microvascular resistance (IMR) on the occurrence of PCI-related myocardial injury and infarction. METHODS: In consecutive patients with stable CAD referred for elective PCI, coronary physiological indexes, including IMR, were measured before and after revascularization. High sensitivity Troponin T (hs-TnT) was assessed up to 24 h after PCI, and PCI-related myocardial injury and type 4a myocardial infarction (MI) were defined according to the fourth universal definition of myocardial infarction. RESULTS: In the 50 patients enrolled, a significant correlation was found between maximum post-PCI hs-Tn and IMR, both at baseline (rho = 0.309, p=0.029) and post-PCI (rho = 0.378, p=0.007). Patients who developed type 4a MI, compared with patients who did not, presented significantly higher IMR levels, both at baseline (28.3 ± 12.2 vs. 19.6 ± 8.8, p=0.020) and post-PCI (45.4 ± 21.3 vs. 21.6 ± 11.2, p<0.0001). Patients with post-PCI IMR > 38 showed significantly higher maximum post-PCI hs-Tn levels (105.4 [49.4-126.9] vs. 22.4 [11.7-38.6] ng/ml, p<0.0001), and developed type 4a MI more frequently (66.8% vs. 4.9%, p<0.0001). CONCLUSIONS: Dynamic changes of microvascular resistance post-PCI are strongly correlated with PCI-related myocardial injury and post-PCI IMR is a strong predictor of type 4a MI in patients with stable CAD undergoing elective PCI.