Microvascular Obstruction in Acute Myocardial Infarction, a Potential Therapeutic Target

Abstract

Microvascular obstruction (MVO) is a recognised phenomenon following mechanical reperfusion in patients presenting with ST-segment elevation myocardial infarction (STEMI). Invasive and non-invasive modalities to detect and measure the extent of MVO vary in their accuracy, suggesting that this phenomenon may reflect a spectrum of pathophysiological changes at the level of coronary microcirculation. The importance of detecting MVO lies in the observation that its presence adds incremental risk to patients following STEMI treatment. This increased risk is associated with adverse cardiac remodelling seen on cardiac imaging, increased infarct size, and worse patient outcomes. This review provides an outline of the pathophysiology, clinical implications, and prognosis of MVO in STEMI. It describes historic and novel pharmacological and non-pharmacological therapies to address this phenomenon in conjunction with primary PCI.

The Use of Thrombectomy during Primary Percutaneous Coronary Intervention: Resurrecting an Old Concept in Contemporary Practice

“…NRP can be assessed invasively using myocardial blush grade (MBG) or index microcirculatory resistance (IMR) [4,9,10]. It can also be detected using a wide range of non-invasive tools such as myocardial contrast echocardiography (MCE), myocardial perfusion scintigraphy (MPS), positron emission tomography (PET), and cardiac magnetic resonance imaging (MRI), which remains the gold standard of identifying and assessing the status of the microcirculation [11][12][13][14][15][16]. Contrast-enhanced cardiac MRI allows the measurement of MVO and is the modality of choice for assessing infarct size.…”

“…Infarct size is a strong predictor of future clinical events beyond left ventricular (LV) ejection fraction and end-systolic volume index (ESVI) [17,18]. In fact, MVO has been proposed to be a surrogate of death and re-admission with heart failure in patients presenting with STEMI [15,19]. Irrespective of the way to assess coronary microcirculation, clinical outcomes are related to its impaired status [19,20], notwithstanding that poor microcirculatory function was also associated with in-hospital major adverse events, persistent ST-segment elevation, impaired LV function, and large infarct size [4,21,22].…”