Cardiac adrenergic innervation within the first 3 months after acute myocardial infarction.
It is widely accepted that myocardial infarction results in adrenergic denervation of the infarcted and peri-infarcted myocardium. On the contrary, the concept of re-innervation of adrenergic nerve fibres is less well established. Although there is evidence of partial re-innervation occuring several months after myocardial infarction, the extent and time scale of re-innervation are only poorly known. In this study we investigated changes in cardiac adrenergic innervation and myocardial perfusion during the early convalescence period (the first 3 months) after an acute myocardial infarction. Single-photon emission computed tomographic imaging was conducted in 15 men 1 week and 3 months after an acute myocardial infarction with I123-metaiodobentzylguanidine (MIBG) and Tc99m-sestamibi (MIBI) to determine the extent of adrenergic denervation and impaired perfusion, respectively. A MIBG and MIBI defect was determined as regional uptake </=30% of maximal myocardial activity. The size of the MIBG defect calculated as a percentage of left ventricular mass remained unchanged between 1 week and 3 months after myocardial infarction (31.1 +/- 17.3% vs. 30. 5 +/- 16.8%, respectively). Accordingly, MIBG activity of the infarct and peri-infarct zones (expressed as a percentage of MIBG activity of the myocardium with normal perfusion) showed no significant change (23.7 +/- 10.0% vs. 25.3 +/- 11.0% and 39.0 +/- 11.3% vs. 40.8 +/- 12.8%, respectively) during the follow-up. On the other hand, the size of MIBI defect decreased significantly during the follow-up (14.2 +/- 11.5% vs. 11.4 +/- 9.7%, P<0.05, respectively) indicating improved myocardial perfusion. The results demonstrate that cardiac adrenergic re-innervation is a slow process; despite a significant increase in myocardial perfusion we found no evidence of adrenergic re-innervation during the first 3 months after acute myocardial infarction.
Simula
S
S
Department of Medicine, Kuopio University Hospital, Kuopio, Finland.
Lakka
T
T
Kuikka
J
J
Laitinen
T
T
Remes
J
J
Kettunen
R
R
Hartikainen
J
J
D019797:3-Iodobenzylguanidine / Q000493:pharmacokinetics; D000320:Adrenergic Fibers / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D002908:Chronic Disease; D004562:Electrocardiography; D005500:Follow-Up Studies; D006321:Heart / Q000000981:diagnostic imaging* / Q000294:innervation*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D009121:Muscle Denervation; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000188:drug therapy; D015425:Myocardial Reperfusion; D017256:Technetium Tc 99m Sestamibi / Q000493:pharmacokinetics; D015912:Thrombolytic Therapy; D013995:Time; D015899:Tomography, Emission-Computed, Single-Photon
D007457:Iodine Radioisotopes; D019797:3-Iodobenzylguanidine; D017256:Technetium Tc 99m Sestamibi