Page 99 - Coronary hemodynamics in acute myocardial infarction - Matthijs Bax

Coronary autoregulation and fatal events in stable CAD
Introduction
Abnormalities in the function and structure of the coronary microcirculation are increasingly recognized as an elementary component in the spectrum of ischemic heart disease. Coronary microvascular alterations may represent an important marker for risk or may contribute to the pathogenesis of myocardial ischemia1 and may arise from a wide array of pathogenetic mechanisms.1 Such alterations may contribute to adverse outcome in patients with stable coronary artery disease (CAD) and may, potentially, offer a target for risk stratification and evaluation of preventive treatment strategies.2
In the absence of significant epicardial disease, the vasodilator response
of coronary circulation, as measured by the coronary flow velocity reserve
(CFVR), is determined by the functional status of the resistance vessels of
coronary microcirculation and can, therefore, be considered a direct marker
of microvascular function.3 Defined as the ratio of hyperemic to basal average 6 peak flow velocity,4 impairment of reference vessel CFVR may originate from
either an increased basal flow velocity or an impaired hyperemic flow velocity. Although there has been interest in the prognostic value of the vasodilatory function of coronary microcirculation,2,5 selective evaluation of basal and hyperemic components of CFVR has not been performed in these investigations. Nonetheless, this discrimination may be particularly important to advance our understanding of processes underlying these vascular alterations and the consequent risk for adverse events.
Therefore, the aim of the present study was to evaluate the association between reference vessel CFVR and long-term fatal events in patients with stable CAD, as well as to document the relative contribution of baseline and hyperemic components in the impairment of reference vessel CFVR.
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