Page 19 - Coronary hemodynamics in acute myocardial infarction - Matthijs Bax

General introduction and outline of the thesis
The microvascular status is a strong prognostic marker of event-free survival.36 1 In clinical practice this marker is not readily available at the time of PPCI for risk stratification.
Wang et al. suggested a clinical risk score to predict no-reflow in PPCI treated STEMI patients comprising 6 items: age, plasma glucose on admission, neutrophil count, Killip class, β-blocker administration and time-to-hospital admission.62 Although no procedural variables were included and the measure of no-reflow was derivative, namely TIMI flow grade and myocardial blush grade, a risk score for clinical use is valuable. Notwithstanding being a practical and simple score for risk stratification, the clinical relevance has to be determined yet in prospective studies.
At the end of last century when we prepared our studies, it was unclear what was the best timing to interrogate the coronary microvasculature, for example at the time of PPCI or a day or a week after reperfusion, as well as by what means, e.g., intracoronary Doppler-derived flow velocity measurements, CMR, contrast echocardiography, angiographically or ECG-derived measurements. Furthermore, in the late 1990s it was unclear when microvascular autoregulation, disturbed by the myocardial infarction, would recover and whether the severity and duration of this dysregulation would affect the recovery of left ventricular function.
Besides changes in flow in the infarct related artery (IRA) during acute myocardial infarction also the non-infarct related arteries (non-IRA) show changes in blood flow and in vasodilator capacity. After patients with single vessel disease had received thrombolytic therapy for myocardial infarction Uren et al. demonstrated in 1994 severe vasodilator abnormalities by PET scans in basal and hyperemic status at 1 week and 6 months after the infarction.63 This disturbed vasodilation function was not only measured in the IRA but also in the non-IRA. Of relevance was the finding that at 6-months follow-up the value in remote myocardium remained lower than that in similar regions in control patients. Thus, myocardial infarction affects vasomotor regulation in the whole cardiac microvascular tree for at least 6 months.
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