Presence of sympathetically denervated but viable myocardium and its electrophysiologic correlates after early revascularised, acute myocardial infarction.
OBJECTIVE
After acute myocardial infarction (AMI), regional denervation exceeding the scar area has been described. We sought to define the electrophysiologic correlates of denervated, but viable, myocardium by combining scintigraphic imaging with extensive electrocardiographic evaluation in AMI patients treated with early reperfusion therapy.


RESULTS
Within 14 days after AMI, 67 consecutive patients underwent radionuclide imaging of myocardial resting perfusion using (201)thallium and of presynaptic sympathetic innervation using (123)I-metaiodobenzylguanidine (MIBG). The mean left ventricular ejection fraction was 58+/-15%. Electrophysiologic studies included evaluation of ventricular repolarisation (resting ECG), depolarisation (signal-averaged ECG), and 24-h Holter monitoring. The perfusion defect, innervation defect, and perfusion/innervation mismatch size of the left ventricle were 14+/-15%, 39+/-22%, and 26+/-16%, respectively. Mismatch was present in 60/67 patients (90%) and correlated with prolonged repolarisation defined by QTc interval (r = 0.40; P < 0.001), and with indexes of delayed depolarisation from signal-averaged ECG (r = -0.32; P = 0.014). Other electrophysiologic parameters did not correlate. During follow-up (4.3+/-1 years) event rates were low, with two cardiac deaths and no severe ventricular arrhythmia causing hospitalisation.


CONCLUSIONS
After early reperfusion for myocardial infarction, viable but denervated myocardium is frequent and correlates with slow depolarisation and repolarisation. However, in patients with small infarct size and preserved left ventricular function, these findings seem to have little influence on outcome.
Simões
Marcus V
MV
Nuklearmedizinische Klinik und Poliklinik, Munich, Germany.
Barthel
Petra
P
Matsunari
Ichiro
I
Nekolla
Stephan G
SG
Schömig
Albert
A
Schwaiger
Markus
M
Schmidt
Georg
G
Bengel
Frank M
FM
D019797:3-Iodobenzylguanidine; D001342:Autonomic Nervous System Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D015716:Electrocardiography, Ambulatory; D004594:Electrophysiology; D005260:Female; D006321:Heart / Q000294:innervation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D009204:Myocardial Revascularization / Q000379:methods*; D009206:Myocardium; D011446:Prospective Studies; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine