Page 77 - Coronary hemodynamics in acute myocardial infarction - Matthijs Bax

Coronary microvascular function and long-term mortality
Introduction
Timely mechanical reperfusion by means of primary percutaneous coronary intervention (PCI) is the optimal treatment strategy in ST-segment–elevation myocardial infarction (STEMI) patients.1,2 Primary PCI aims at immediate restoration of epicardial vessel patency and subsequent reperfusion of myocardial tissue. Inadequate myocardial reperfusion at the microvascular level is known to be associated with larger infarct size, lower residual left ventricular function, and increased mortality at follow-up.3–8 Although epicardial vessel patency is restored successfully in most primary PCI procedures, microvascular reperfusion can be inadequate even when optimal angiographic epicardial reperfusion is achieved.9,10
Intracoronary-derived Doppler flow velocity measurements allow sensitive 5 assessment of microvascular function in clinical practice.9,11 The Doppler flow velocity–derived parameters coronary flow velocity reserve (CFVR), diastolic deceleration time (DDT), and early systolic retrograde flow (SRF) in the infarct-
related coronary artery were shown to correspond to the extent of microvascular dysfunction after reperfusion for STEMI.12 Moreover, several studies have indicated that CFVR in the infarct-related artery assessed after primary PCI is the most valuable prognostic marker of recovery of left ventricular function after STEMI.7,8,13–17
However, although microvascular dysfunction is considered an important marker for risk, and a possible target for adjunct therapies,11,18,19 limited interest has focused on its potential prognostic value for long-term clinical outcome. Moreover, although microvascular alterations have additionally been reported to occur at a distance from the infarcted myocardium, the prognostic value of microvascular function in a reference vessel for long- term clinical outcome after mechanical reperfusion for STEMI has not been investigated.20
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