Cardiac adrenergic denervation in patients with non-Q-wave versus Q-wave myocardial infarction

In spite of smaller infarct size and better preserved left ventricular func tion the long-term prognosis after a non-Q-wave infarction is not better th an after a Q-wave infarction. In fact, the risk of sudden cardiac death is higher in patients with a non-Q-wave infarction than in patients with a Q-w ave infarction. One possible reason for postinfarction arrhythmias is cardi ac adrenergic denervation resulting from myocardial infarction. In this stu dy we compared cardiac adrenergic innervation after non-Q-wave and Q-wave i nfarctions. Single-photon emission tomography using iodine-123 metaiodobent zylguanidine (MIBG) and technetium-99m sestamibi (MIBI) tracers were conduc ted in order to compare cardiac adrenergic denervation and myocardial perfu sion in 12 patients with a non-Q-wave infarction and 15 patients with a Q-w ave infarction. MIBG and MIBI defects were determined as regional uptake 13 0% of maximal myocardial activity. The size of MIBI defects calculated as a percentage of left ventricular mass was significantly smaller in patients with a non-Q-wave infarction than in patients with a Q-wave infarction (4%/-3% vs 9%+/-7%, P<0.05, respectively). According to the maximal serum crea tine kinase activity, less myocardium was damaged in patients with a non-Q- wave infarction than in patients with a Q-wave infarction (502+/-436 IU/l v s 1878+/-1265 IU/l, P<0.001). In spite of this, the extent of MIBG defects was similar in patients with a non-Q-wave and patients with a Q-wave infarc tion (21%+/-18% vs 23%+/-12%, respectively). In addition, the size of MIBG defect correlated with the infarct size (maximal creatine kinase activity) (r=0.52, P<0.05) after a Q-wave infarction but not after a non-Q-wave infar ction. In conclusion, despite a smaller infarct size in non-Q-wave infarct patients, the extent of cardiac adrenergic denervation was similar in patie nts with a non-Q-wave and patients with a Q-wave infarction. In addition, t he extent of cardiac adrenergic denervation was related to the infarct size in patients with a Q-wave infarction but not in patients with a non-Q-wave infarction.