Abstract
Objectives We aimed to identify mechanical and pharmacological revascularization strategies correlated with the index of microcirculatory resistance (IMR) in ST-elevation myocardial infarction (STEMI) patients. Background Microvascular dysfunction (MVD) after STEMI is correlated with infarct size and poor long-term prognosis, and the IMR is a useful analytical method for the quantitative assessment of MVD. However, therapeutic strategies that can reliably reduce MVD remain uncertain. Methods Patients with STEMI who underwent primary percutaneous coronary intervention (PCI) were enrolled. The IMR was measured with a pressure sensor/thermistor-tipped guidewire immediately after primary PCI. High IMR was defined as values ≥66th percentile of IMR in enrolled patients (IMR > 30.9 IU). Results A total of 160 STEMI patients were analyzed (high IMR = 54 patients). Clinical factors for Killip class (P=0.006), delayed hospitalization from symptom onset (P=0.004), peak troponin-I level (P=0.042), and multivessel disease (P=0.003) were associated with high IMR. Achieving final thrombolysis in myocardial infarction myocardial perfusion grade 3 tended to be associated with low IMR (P=0.119), whereas the presence of distal embolization was significantly associated with high IMR (P=0.034). In terms of therapeutic strategies that involved adjusting clinical and angiographic factors associated with IMR, preloading of third-generation P2Y12 inhibitors correlated with reducing IMR value (β = −10.30, P < 0.001). Mechanical therapeutic strategies including stent diameter/length, preballoon dilatation, direct stenting, and thrombectomy were not associated with low IMR value (all P > 0.05), and postballoon dilatation was associated with high IMR (β = 8.30, P=0.020). Conclusions In our study, mechanical strategies were suboptimal in achieving myocardial salvage. Preloading of third-generation P2Y12 inhibitors revealed decreased IMR value, indicative of MVD prevention.
Highlights
ST-elevation myocardial infarction (STEMI) is usually caused by complete occlusion of a major epicardial coronary artery and results in myocardial ischemia and cell death
Many previous studies demonstrated that coronary microvascular dysfunction (MVD) was correlated with infarct size, and the presence of MVD was associated with an increased risk of cardiovascular events
Distal embolization of atheromatous debris, swelling of cardiomyocytes associated with interstitial edema, and reperfusion-related myocardial injury after primary percutaneous coronary intervention (PCI) is Journal of Interventional Cardiology considered as the major mechanism of microvascular damage [5,6,7,8,9,10]
Summary
ST-elevation myocardial infarction (STEMI) is usually caused by complete occlusion of a major epicardial coronary artery and results in myocardial ischemia and cell death. Many previous studies demonstrated that coronary microvascular dysfunction (MVD) was correlated with infarct size, and the presence of MVD was associated with an increased risk of cardiovascular events. Distal embolization of atheromatous debris, swelling of cardiomyocytes associated with interstitial edema, and reperfusion-related myocardial injury after primary PCI is Journal of Interventional Cardiology considered as the major mechanism of microvascular damage [5,6,7,8,9,10]. E index of microcirculatory resistance (IMR) can provide a quantitative assessment of the microvascular function of epicardial stenosis and hemodynamic condition independently. Recent studies demonstrated that IMR assessed immediately after primary PCI is well correlated with the recovery of left ventricular function in STEMI [1, 7]
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