The relation between early ventricular tachycardia and QT dispersion in patients with acute myocardial infarction treated with thrombolytic therapy

Abstract

In this study, we investigated the influence of increased QT dispersion (defined as maximal QT interval minus minimal QT interval) on the occurrence of early non-sustained ventricular tachycardia (NSVT) in patients with acute myocardial infarction (AMI) who received thrombolytic therapy. In the retrospective analysis of 96 patients with clinical reperfusion criteria, 36 had NSVT within the first 12 hours after the onset of thrombolytic therapy (group A), and 60 patients did not have NSVT during the same period (group B). On admission ECG, QT and QT_c dispersion and the amount of jeopardized myocardial area (Aldrich score) were calculated. In group A, Aldrich score was significantly higher (21.4 ± 7.2% vs 14.2 ± 4.9%;p < 0.005). There were significantly higher QT dispersion values on admission (83.3 ± 23.4 vs 67.5 ± 23.7 msec;p < 0.005), at 24th hour (87.1 ± 12.6 vs 72.1 ± 27.4 msec;p < 0.005) and on the 10th day (63.5 ± 31.2 vs 49.5 ± 14.3 msec;p < 0.005) in group A. In subgroup analysis of group A, patients with NSVT between 6–12 hours (group A2) had significantly higher Aldrich score and QT dispersion values at all above time points compared to patients with NSVT between 0–6 hours (group A1) after AMI. In conclusion, in this study we found a strong relation between the occurrence of NSVT within 12 hours and increased QT dispersion on admission ECG in patients with AMI who received thrombolytic therapy. This relation was even stronger for the subgroup of patients with NSVT within 6–12 hours. Thus, these results may indicate that NSVT is related to increased QT dispersion which is secondary to larger jeopardized myocardial area in patients with AMI.