Page 127 - Coronary hemodynamics in acute myocardial infarction - Matthijs Bax

Recovery of microvascular dysfunction following STEMI
Discussion
In our study, we found supporting evidence on the importance of the microvasculature status following STEMI. Microvascular dysfunction in the subacute phase, as measured with CFR, contrary to HMRI, was associated with LVEF at both four months and two years assessed with CMR. Second, an impaired CFR in the subacute phase was associated with alterations in diastolic volume. Finally, improvement in CFR was concurrently associated with improvement in LVEF between baseline and four months in patients with a large infarct size.
The added value of the current study compared to previous studies stems from the systematically obtained intracoronary Doppler flow measurements and CMR imaging at similar time points and at two years. This provides insights into the recovery of microvascular dysfunction and whether this is associated with LVF recovery. Results of previous studies support the prognostic importance of microvascular function following STEMI. These studies used different diagnostic modalities for the assessment of microvascular function, including myocardial contrast or transthoracic Doppler echocardiography5,13-15.
Bax et al reported that CFR measured directly after PPCI in anterior STEMI 7 was the only predictor of LV improvement at six months as assessed by echocardiography. However, the mean peak CK-MB was not included in the multivariate model since the aim of the study was to assess early determinants
(at the time of reperfusion) of LVF recovery. In the current study, however, CFR in the subacute phase was not independently associated with LVEF at two years but peak CK-MB was independently associated. This observation could be the result of several factors. First, the small number of patients limits the ability to perform a reliable multivariate regression model. Second, CFR measured in the subacute phase is associated with infarct size, as measured by maximum CK-MB16. From a pathophysiological perspective, the ability of the coronary microvasculature to vasodilate is related to the severity of the initial myocardial injury. In our study, we also observed that patients with large infarct sizes had a significantly lower CFR. Consequently, it is difficult to determine whether CFR is a marker of larger infarcts or whether impaired microvascular function has a primary role in adverse LV remodeling. Nonetheless, CFR in the subacute phase of STEMI is associated with LVF at both four months and two years. In order
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