Copyright © 2004 by the European Society of Cardiology.
Clinical research
Presence of sympathetically denervated but viable myocardium and its electrophysiologic correlates after early revascularised, acute myocardial infarction
a Nuklearmedizinische Klinik und Poliklinik, Munich, Germany
b Medizinische Klinik, Technische Universität München, Munich, Germany
* Corresponding author. Tel.: +49-89-4140-2984/2971; fax: +49-89-4140-4950
E-mail address: frank.bengel{at}lrz.tum.de
E-mail address: frank.bengel{at}lrz.tu-muenchen.de
Received 11 September 2003; revised 13 January 2004; accepted 13 February 2004
Abstract
Aims 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.
Methods and results Within 14 days after AMI, 67 consecutive patients underwent radionuclide imaging of myocardial resting perfusion using 201thallium and of presynaptic sympathetic innervation using 123I-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 (
; 
), and with indexes of delayed depolarisation from signal-averaged ECG (
; 
). 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.
Key Words: Myocardial infarction • Electrophysiology • Radioisotopes • Sympathetic nervous system • Imaging
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