High frequency ECG during reperfusion therapy of acute myocardial infarction

The very high-frequency components of the QRS complex are examined to test their ability to detect effects of reperfusion therapy of acute myocardial infarction using thrombolytic agents. Surface electrocardiogram (ECG) waveforms from the standard lead V₅ were averaged (128 waveforms) 15 and 90 minutes after the administration of the thrombolytic agent. The averaged waveforms from each time segment were then bandpass-filtered between 150 and 250 Hz using the fast-Fourier-transform algorithm and were used to compute the root-mean-square (RMS) voltage of the filtered QRS complex. It is found that after successful reperfusion, when coronary blood flow is reestablished, the RMS voltage of the high frequency QRS complexes increases. In patients with unsuccessful reperfusion, the RMS voltage decreases. These changes in the high frequency QRS complex may be related to salvaging myocardium and may provide useful information about the reperfusion of acute myocardial infarction