Microvascular function before PCI was found to be an important determinant of periprocedural MI and may allow the prospective identification of patients at risk for periprocedural MI.
The study, which was published in Heart, involved 54 patients with stable angina who had their index of microvascular resistance (IMR) measured before and after PCI in a culprit vessel. Researchers calculated the relative pre-IMR ratio (rPIMR), which was defined as IMR culprit divided by IMR nonculprit, and sampled troponin 24 hours after PCI.
According to study results, mean troponin after PCI was 0.37 ± 0.8 ng/mL, and 33 (61%) patients fulfilled the criteria for periprocedural MI. The most significant indicator of post-PCI troponin was IMR before PCI (P=.001), but the number of balloon inflations (P=.02) and rPIMR (P=.017) was also indicative. Patients with periprocedural MI vs. patients without periprocedural MI had the higher IMR before PCI (P=.02).
Overall, the strongest predictor of troponin after PCI was IMR before PCI (P=.02), and both IMR before PCI (P=.026) and rPIMR (P=.03) were predictive of periprocedural MI.
“This is the first study to demonstrate that the pre-PCI IMR independently identifies periprocedural MI in stable patients undergoing elective PCI, and that a novel ratio, the rPIMR, is also predictive of PPMI,” the researchers wrote. “Future studies in a larger cohort are required to establish the predictive ability of IMR in periprocedural MI, and whether a targeted strategy aimed at reducing IMR pre-PCI leads to improved outcomes.”