engleski

The QT interval in Q wave and non-Q wave acute myocardial infarction

Aim. To analyze the QT interval in various types (Q wave and non Q-wave) and locations of acute myocardial infarction (AMI). Methods. Data were obtained and analyzed in 605 patients who suffered their first myocardial infarction. The patients were divided into two groups: patients with Q-wave AMI (QAMI, N = 565) and patients with non Q-wave AMI (NQAMI, N = 40). QT interval, cumulative serum creatine kinase, serum potassium and calcium concentrations, incidence of malignant ventricular arrhythmias (tachycardia and fibrillation), the effect of drugs with potential influence on QT interval duration and thrombolytic therapy were analyzed. The corrected QT interval (QTc) was calculated according to Bazett´s formula. The QT interval was determined twice: on the second day and during the third week after the onset of AMI. Results. The QTc interval was found to be significantly longer in the acute stage of infarction in the NQAMI group (0.478 ± ; ; 0.003 sec vs. 0.477 ± ; ; 0.001 sec, p<0.001), but the difference was no longer significant during the third week of illness (0.442 ± ; ; 0.002 sec vs. 0.441 ± ; ; 0.001 sec, NS). Patients who received thrombolysis, regardless of myocardial infarction type, were found to have a significantly shorter QTc interval than patients who did not receive this treatment (0.440 ± ; ; 0.003 sec vs. 0.452 ± ; ; 0.002 sec, p<0.001). Enzymatically estimated infarct size was larger in QAMI patients. There were no significant differences between groups regarding other variables. Conclusions. Our results support the hypothesis that the QT interval duration is not related to the extent of myocardial necrosis, but possibly to the amount of residual ischemic myocardium.

Myocardial infarction; QT interval; Q wave infarction; non-Q wave infarction

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