THE PERSISTENCE OF HIBERNATING MYOCARDIUM AFTER ACUTE MYOCARDIAL-INFARCTION

Objective To establish the persistence of hibernating myocardium initi ally detected after myocardial infarction treated with thrombolysis. M ethods and results Fourteen patients underwent gated positron emission tomography with 18-fluoro-deoxyglucose and N13-ammonia at a median of 8 days after first myocardial infarction. Repeat scans were performed at a median of 13 weeks post-infarction. A total of 148 (30.9%) myoca rdial segments showed reduced N13-ammonia uptake at the time of the fi rst scan compared with 154.5 (32.2%) segments at the time of repeat im aging. The median change in the number of segments with reduced perfus ion was -1.0. Initially 13 subjects had hibernating myocardium, seven patients had large areas and six had smaller regions. Six (46.2%) subj ects had repeat scans showing unchanged areas of hibernating tissue an d seven had second scans demonstrating changes in the size of the regi on of hibernating myocardium. One patient had no hibernating myocardiu m on either scan.Conclusions Positron emission tomography performed se veral months after myocardial infarction demonstrates significant chan ges in myocardial perfusion. However, a reduction in the number of seg ments with reduced perfusion does not always result in an improvement in myocardial metabolism and contraction. Whilst most regions of hiber nating myocardium were still present several months after infarction, in only approximately half was the size of the mismatched region uncha nged. Therefore it is not possible to predict the fate of hibernating myocardium which is present after infarction.