SIGNAL AVERAGED - ECG AND HEART FAILURE IN ACUTE MYOCARDIAL INFARCTION - ELECTROPHYSIOLOGY CHANGES IN CARDIOVASCULAR CONTINUUM
Introduction: Signal averaged ECG (SAECG) is a simple and non invasive method for detecting presence of late ventricular potentials (LP). Patients with acute myocardial infarction (AMI) have arythmogenic substrate presented by occurrence of LP. The aim of this study was to evaluate correlation between congestive heart failure (CHF) in acute myocardial infarction (AIM) and SAECG parameters as well as their predictive value considering CHF occurrence during first year period after AMI.
Patients and methods: We analyzed occurrence of CHF in acute phase and one year after AMI in 86 patients with AMI and present LP and 102 AMI patients without LP as a control group. Late potentials were detected through signal averaged ECG recording and its three parameters: QRS duration (QRSd), low amplitude high frequency duration (LAHFd) and root mean square in last 40ms (RMS (40ms)). Criteria for their presence were QRSd longer than 114ms, LAHFd longer than 38ms and RMS (40ms) less than 20 microV. At least two of those three parameters with abnormal values indicated LP presence. There were no significant differences between groups towards sex and age.
Results: There were 30.2% patients with AMI and LP presented who had CHF in acute phase comparing to 27.5% of patients with AMI but without LP. During one year period, presence of LP did not indicate CHF development also. 33.3% patients with abnormal RMS (40ms) had CHF in acute phase comparing to 10.5% patients with normal values of this parameter. Multivariate analyze showed that this parameter was significant predictor of development of CHF in one year period after AMI (p<0.05).
Conclusions: Left ventricle remodeling after AMI develops myocardial structural changes which contribute to abnormal - delayed impulse conduction. Electrical changes, presented through a parameter of SAECG RMS (40ms) are, therefore, significant part in cardiovascular continuum of CHF.