Aims: Analyses of ST-segment resolution during acute myocardial infarction has, during recent years, challenged coronary angiography as gold-standard for predicting myocardial reflow and future risk. We have previously reported that continuous ST-monitoring can be done accurately in the clinical setting. We now set out to compare the prognostic value of previously suggested cut-offs for ST-segment resolution, and determine the times to measure these.
Methods and results: We analysed 752 patients with ST-elevation infarction, from the second Assessment of Safety and Efficacy of a New Thrombolytic (ASSENT 2) and ASSENT-PLUS studies, either with vectorcardiography or continuous 12-lead ST-monitoring. All analyses were made blindly by two independent observers. Times to 20, 30, 50 and 70% ST-segment resolution were examined in relation to 30-day mortality.The optimal cut-off for ST-segment resolution analyses was found to be 50%, measured at 60 min. We could hereby identify a large low-risk group, 40% of the population, with only 1.4% 30-day mortality. Furthermore, 88% of deaths were correctly predicted within 1h of observation and treatment.
Conclusion: Continuous ST-monitoring of patients with acute myocardial infarction yields important prognostic information after 60 min of observation and should be used for very early-risk stratification in these patients.