Myocardial infarct size measurement using geometric angle calculation.

ABSTRACT

BACKGROUND: In basic cardiovascular research focusing on animal models of myocardial infarction (MI), the measurement of infarct size is performed by planimetry of histological sections of the heart. However, in the setting of chronic MI with ongoing changes in ventricular geometry caused by wall thinning and hypertrophy, the scar area tends to become smaller. MATERIALS AND METHODS: Here, in this study we compared infarct measurements in tissue sections (of rat and porcine hearts) based on three different calculation approaches, that is, infarct area, infarct lengths and infarct angles utilizing the centroid of the left ventricle using a newly developed calculation approach. RESULTS: Infarct sizes from all three measurement approaches showed significant correlation with parameters of cardiac function. However, results derived from area measurements were significantly smaller than those obtained using the other two measurement approaches due to scar thinning (infarct size area 14·81% ± 1·27 SEM, length 23·94% ± 2·04 SEM, angle 24·75% ± 2·13 SEM, P < 0·0001, n = 30). Moreover, results from angle measurements evidenced a much better correlation with parameters of cardiac function in a small animal model of chronic MI (e.g. ejection fraction, angle r = -0·73; length r = -0·64; area r = -0·59, n = 30) as well as in a large animal model of acute MI (angle r = -0·82; area r = -0·67, n = 10). CONCLUSIONS: We concluded that area-, length- and angle-based measurements can be used to determine the relative infarct size in acute MI models, although an area-based measurement might be less accurate in the setting of chronic MI. Our new method of infarct angle measurement is a reliable and simple way to calculate infarct size compared with conventional measurement approaches.