IN-SITU APOPTOSIS ASSAY FOR THE DETECTION OF EARLY ACUTE MYOCARDIAL-INFARCTION

Detection and age determination of myocardial infarction (MI) is often necessary in both clinical and pathological settings. Conventional hi stopathological techniques are of limited utility in the demonstration of myocardial ischemic cell death (MICD) within the first 6 hours of MI. In this study, an in situ apoptosis assay was evaluated for the de termination of early MICD or early MI. Sections of formalin-fixed, par affin-embedded archival tissue blocks from 80 hearts were stained for the presence of apoptotic cells by specific labeling of nuclear DNA fr agmentation. conventional hematoxylin and eosin stain showed acute Mi (group A, n = 32), equivocal evidence for MICD or early infarction (gr oup B, n = 35), or no abnormal findings (group C, n = 13). The sensiti vity and specificity of he in situ apoptosis assay for MICD were confi rmed in groups A and C patients. We showed that apoptosis of myocardia l cells can occur after ischemic myocardial cell injury. Virtually all documented cases of acute MI (group A) revealed a sizeable distributi on of apoptosis cells visible on gross examination of glass slides. Sp ecial attention was given to patients in group B, who were at high ris k for MI and for suspected but not proved cardiac death. In this group , 34/35 cases (97%) showed focal or diffuse nuclear positivity of vary ing degrees for apoptosis, confirming the presence of MICD. A sizeable distribution of apoptotic cells, similar to that observed in group A, was noted in 13/35 cases (37%) of group B, suggesting acute MI in the se cases. The in situ assay of DNA fragmentation can detect MICD while the histological diagnosis is still inconclusive. It is estimated tha t with this assay one can detect MICD as early as 2 to 4 hours.