452 Medicina (Kaunas) 2012;48(9) Medicina (Kaunas) 2012;48(9):452-7 t-Wave normalization During Follow-up after early and late Mechanical Recanalization of Infarct-Related artery With and Without stent Implantation Eglė Kalinauskienė, Albinas Naudžiūnas Department of Internal Diseases, Medical Academy, Lithuanian University of Health Sciences, Lithuania Key Words: electrocardiogram; myocardial infarction; percutaneous coronary intervention. Summary. Objective. The aim of this study was to evaluate T-wave normalization during the 6-month follow-up in the patients who underwent early or late mechanical recanalization of the infarct-related artery with and without stent implantation. Material and Methods. A total of 248 consecutive patients were divided into the following groups: early angioplasty (≤24 hours) without (n=114) or with stents (n=6) and late angioplasty (>24 hours) without (n=114) or with stents (n=14). The changes in T-wave recovery, QRS score, and echocardiographic left ventricular ejection fraction were compared between the groups. Results. At 3 months, a greater percentage of patients in the group of early angioplasty with st- ents had again positive T wave than in the group of early angioplasty without stents (75% vs. 35%, P=0.05). After 6 months, all patients in the group of early angioplasty with stents had again positive T wave. A signifcant increase in left ventricular ejection fraction after 3 months was also observed only in the groups of early angioplasty, especially that with stents (30.0% [SD, 3.5%] vs. 38.4% [SD, 5.2%], P=0.008). However, there was no signifcant difference in the QRS score in this group com- paring the data at discharge and after 3 months (5.4 [SD, 4.3] vs. 5.0 [SD, 1.9], P>0.05). Conclusions. The group of early angioplasty with stents showed the best recovery of T wave and left ventricular ejection fraction, but the QRS score did not change significantly from discharge to the 3-month follow-up, so the evolution of T wave corresponded to an improvement in ejection frac- tion at follow-up better than the evolution of QRS score. Correspondence to E. Kalinauskienė, Department of Internal Medicine, Medical Academy, Lithuanian University of Health Sciences, Josvainių 2, 47144 Kaunas, Lithuania E-mail: eglekalin@yahoo.com Introduction Primary percutaneous coronary intervention (PCI) with stent implantation has become accept- ed as the preferred interventional strategy in ST- segment elevation myocardial infarction (STEMI) (1, 2). Myocardial reperfusion therapy results in bet- ter function of the left ventricle (LV) and improved survival after acute myocardial infarction (AMI) in cases of early and successful recanalization of the infarct-related artery (IRA) and complete myocar- dial reperfusion, but late recanalization (3 or more days after AMI) or incomplete myocardial reperfu- sion is associated with an increased risk of death and LV dysfunction (3, 4). However, recently Sone et al. have reported a remarkable recovery of a 65-year- old man with marked ST-elevation myocardial in- farction, who was treated with PCI more than 2 days after onset (5). Whilst an improvement in perfusion is the usual fnding after successful angioplasty, there is considerable disparity between the angiographic appearance of restored TIMI fow in IRA and the electrocardiographic (ECG) signs of myocardial tis- sue reperfusion insuffciency manifested by persis- tent ST-segment elevation after recanalization (6). Ito et al. (7) demonstrated that the restoration of normal epicardial blood fow was not suffcient to ensure adequate myocardial reperfusion; the latter required perfusion at the level of the coronary mi- crocirculation and myocytes. Myocardial perfusion in the distribution of the dilated artery was shown to improve progressively up to 3 months, but thereaf- ter, no improvement was seen (8, 9). Despite the changes in ST-segment deviation amplitude have been extensively studied, the signif- cance of T-wave changes is less clear, especially in the follow-up period. Only few studies have inves- tigated the signifcance of T-wave direction in leads with ST-segment elevation (10). ST-segment or T- wave changes may be secondary to the abnormali- ties of depolarization, i.e., pre-excitation, or abnor- malities of QRS voltage or duration. On the other hand, ST-segment and T-wave abnormalities may be unrelated to any QRS abnormality, and in this case, they are called primary repolarization abnor- malities. These are caused by ischemia, pericarditis, myocarditis, drugs (digoxin, antiarrhythmic drugs), and electrolyte, particularly potassium, abnormali- ties. T-wave inversion in the anterior precordial leads may be seen in cases of acute pulmonary embolism, while fattened T waves with prominent U waves and ST-segment depression may refect hypokalemia or effect of digitalis therapy. There are a wide variety