Serial analyses of ventricular late potentials in patients with reciprocal ST segment changes during acute myocardial...

The aim of this study was to determine whether successful reperfusion may alter substrate that is responsible for late potentials in the presence or absence of reciprocal ST segment changes (RC). The study population consisted of 50 patients (27 with RC and 23 without RC) with anterior acute myocardial infarction (AMI) undergoing successful thrombolytic therapy (TT). The presence of reciprocal changes was defined as ST-segment depression >1 mm, measured 80 ms after the J point in at least 2 leads other than those reflecting the infarct on admission ECG. All patients were evaluated with coronary angiography at predischarge. Signal averaged ECG (SAECG) recordings were obtained before and 10 days after TT. Baseline characteristics, SAECG findings, and angiographic data were similar between the groups. The only different baseline finding was the time from symptom onset to TT (204 +/- 150 minutes for patients with RC vs 312 +/- 174 minutes for patients without RC. P = 0.021). After TT, RMS values improved in patients with RC (from 35 +/- 17 microV to 43 +/- 14 microV, P = 0.038) and LAS and RMS were significantly better in this group. However, patients without RC did not show any changes in SAECG parameters after TT. LV ejection fraction (10th day) was better in patients with RC (45 +/- 11% vs 39 +/- 6%, P = 0.014). The frequency of ventricular arrhythmias during the hospitalization period was also similar between the groups. Reciprocal ST depression that regresses simultaneously with the infarction related ECG changes after TT in anterior AMI seems to be related to the time that has elapsed since the symptom onset. The improvement in SAECG parameters after TT in these patients is probably the result of earlier reperfusion leading to less myocardial damage.