STEMI Onset Time | Journal Scan

Study Questions:

What is the relation between symptom onset time and actual onset time of ST-segment elevation myocardial infarction (STEMI)?


The authors used the Mayo Clinic Percutaneous Coronary Intervention (PCI) Registry to obtain baseline, procedural, and outcome data on 607 patients undergoing primary PCI for STEMI. Biochemical onset time was determined by backward extrapolation of serial increasing cardiac troponin T (cTnT) measurements.


The median patient-reported onset time was 12 minutes later than the calculated time of first cTnT increase and was therefore estimated to be 4.2 hours later than the biochemical onset time (interquartile range, 1.9-11.1; p < 0.001). The study assumed a 4-hour interval between coronary occlusion and first cTnT increase. Conventional ischemic time showed no association with infarct size or outcome; however, after recalculation of ischemic time with biochemical onset time, significant associations with infarct size (r2 = 0.14; p = 0.001) and 1-year mortality (hazard ratio, 1.70 per doubling; 95% confidence interval, 1.20-2.40; p = 0.003) were found. As the underestimation of ischemic time by patient-reported onset time increased, there was a corresponding increase in the risk of mortality.


The authors concluded that symptom onset time underestimates the time of onset of STEMI.


Despite biological plausibility to the contrary, most prior studies have failed to demonstrate a strong association between ischemic time (as calculated by symptom to reperfusion time) and outcome in patients undergoing primary PCI. This study suggests that patient-reported symptom onset time underestimates the onset of myonecrosis, and that biological time to reperfusion is better correlated with outcome. The outcome of patients undergoing primary PCI has remained unchanged in the last decade, and more upstream efforts are needed to reduce biological ischemic time and reduce early and late mortality in this population.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention

Keywords: Biochemical Processes, Biological Markers, Coronary Occlusion, Ischemia, Mortality, Myocardial Infarction, Percutaneous Coronary Intervention, Registries, Risk, Troponin T, Reperfusion

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