The objective of this study was to relate the number of ventricular arrhythmias (VA) to the normalization time of the ST segment during thrombolysis for acute myocardial infarction. The 24 h Holter recordings, begun on start of intravenous thrombolytic therapy, and the 12-lead electrocardiograms of 41 patients with a patent infarct-related artery according to coronary angiography were analysed. The mean time from onset of chest pain to angiography was 30.5±3.1 h, ≥24 h in 59%. The normalization time of the ST segment, assessed by the time of decrease of ST segment elevation from start of Holter recording to normal or steady state was ≥60 min in 13 patients (group 1), 60 to 180 min in 15 patients (group 2) and > 180 min in 13 patients (group 3). The incidence of VA was similar in all groups, except for ventricular tachycardias (VT) >15 beats (group 1:69%, group 2:13%, group 3:15%, P=0.002) The frequency of accelerated idioventricular rhythms (AIVR), early AIVR (≤6 h) and of VT was significantly higher in group 1 than in group 3 with a 8-, 30- and 6- fold increase, respectively (back transformed mean). We conclude that the number of V As is related to the normalization time of the ST segment during reperfusion. This may suggest that faster reflow is more arrhythmogeni
