Page 121 - Coronary hemodynamics in acute myocardial infarction - Matthijs Bax

Recovery of microvascular dysfunction following STEMI
hyperenhancement, expressed as a percentage of LV mass8. Transmurality was determined by dividing the hyperenhanced area by the total area of the predefined segment. MVO was defined as any region of hypoenhancement within the hyperenhanced infarcted area8. CMR data were analyzed in a core lab using a dedicated software package (Mass 2008 beta; Medis, Leiden, the Netherlands), blinded to the intracoronary Doppler flow measurements.
Statistical analysis
Normally distributed data are expressed as mean(±SD) and for non-normally distributed data the median value (25th to 75th percentile) is provided. Categorical variables are presented as number (%) and compared by the chi- square test. A Student’s t-test or a one-way analysis of variance was used to compare data with a normal distribution of continuous variables and a Kruskal- Wallis test for non-normally distributed continuous variables.
A univariate linear regression model was used to assess whether CFR and HMRI measured in the subacute phase were associated with global left ventricular volumes and function at baseline, four months and two years.
In a subsequent multivariate linear regression model, the prognostic value 7 of CFR in the subacute phase was assessed with other known patient and angiographic characteristics associated with LVEF (%) at two years11,12. Based
on the cut-off value of CFR <2, patients were classified into those with an
impaired (CFR <2) or preserved microvascular function (CFR ≥2) at baseline. LVEF, LVEDV and LVESV index measured at baseline, four months and at two years were compared in both groups. The temporal change in LVEF, LVEDV and LVESV index was also compared between the groups.
Whether improvement in CFR and HMRI within the initial four months was concurrently associated with improvement in LVEF was investigated for two different infarct size groups stratified according to the median infarct size.
A p-value <0.05 was considered statistically significant. All statistical analysis was performed using SPSS software, Version 20.0 (IBM Corp., Armonk, NY, USA).
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