Non-invasive detection of early infarct vessel patency by resolution of ST-segment elevation in patients with thrombolysis for acute myocardial infarction; results of the angiographic substudy of the Hirudin for Improvement of Thrombolysis (HIT)-4 trial.

Aims The purpose of this study was to validate ST segment resolution as a non-invasive marker for patency of the infarct-related artery 90 min after the start of streptokinase therapy in patients with acute myocardial infarction. Methods and Results In the HIT-4 angiographic substudy, 447 patients with acute myocardial infarction or =70% ST resolution (n=70) had a 92% probability of TIMI 2/3 flow, while <30% ST resolution (n=172) was associated with the absence of TIMI 3 flow in 84% of patients. Conclusions Despite fairly good sensitivities and specificities the prediction of infarct vessel patency by ST resolution in the individual patient is limited. However, patients with > or =70% ST resolution are likely to have a patent infarct artery and <30% ST resolution predicts epicardial vessel occlusion or, since persistent ST elevation reflects the existing ischaemic myocardial injury, absence of myocardial perfusion.