Page 185 - Coronary hemodynamics in acute myocardial infarction - Matthijs Bax

Since reduction of baseline microvascular resistance, not increase of hyperemic resistance, is the main driver of the lower CFR it is suggestive that impaired basal microvascular autoregulation plays a pivotal role as opposed to a diminished vasodilator reserve.
Chapter 7 describes the results of the research into a subpopulation from the HEBE study. It concerns 62 patients who underwent a PPCI for AMI. The HEBE study was designed to evaluate the effect of bone marrow mononuclear cell therapy on left ventricle improvement after STEMI. In this sub-study, Doppler- derived intracoronary hemodynamic evaluation was performed within 1 week and after 4 months after PPCI. Outcomes are related to left ventricular function (LVF) determined by CMR at 4 days, 4 months, and 2 years. CFR was not significantly associated with LVEF at 2 years in a multivariate regression model. This is in contrast to the findings described in chapter 2. CFR measurement was performed 1 to 4 days after reperfusion. The CFR may have increased in the first few days after reperfusion due to a decreased hyperemic microvascular resistance. The lower CFR in larger sized infarctions, mainly based on higher hyperemic microvascular resistance (and thus lower blood flow velocity) also plays a role. Subdivision by infarct size (separated by the median infarct size of 24.2% of LV on CMR) showed an association between absolute CFR improvement and LVEF improvement in patients with larger infarcts. Also, patients with a greater decrease in hyperemic microvascular resistance showed significant improvement in LVEF. Neither effect was seen in the group with smaller infarcts.
To elaborate on factors influencing microvascular dysfunction during acute anterior wall myocardial infarction, we described in Chapter 8 the influence of serum glucose levels in non-diabetics on blood flow velocity and microvascular resistance in the IRA and non-IRA. In some patients, stress-related metabolic changes in the acute phase of the infarct led to glucose intolerance and elevated serum glucose levels. Serum glucose values were significantly associated with peak troponin T levels. In the adjusted multivariate analysis, elevated glucose levels were significantly associated with decreased baseline microvascular resistance (i.e., higher baseline flow velocity) and decreased CFR in the non-IRA. This association disappeared at 1-week and 6-months follow-
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Summary - Samenvatting
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