Key Points
- To determine whether coronary reperfusion via thrombolysis reduces electrocardiographically estimated infarct size and evaluate if baseline ST-segment elevation can predict individual myocardial salvage.
- Assessed patients presenting with anterior acute myocardial infarction within 6 hours of onset receiving analgesia only (n = 35) or thrombolytic therapy with intracoronary streptokinase or intravenous anistreplase (n = 33).
- Calculated baseline ischemic injury from the initial 12-lead ECG ST-segment elevation area (sigma ST area) and evaluated 48-hour evolved infarct size using a QRS scoring system, validating predictive capacity in a separate cohort (n = 22).
- Initial potential infarct size was comparable between analgesia-only (sigma ST area = 115 ± 60 mm²) and thrombolysis groups (126 ± 77 mm²), while evolved QRS score at 48 hours was significantly lower in the thrombolysis group (4.1 ± 2.5 vs 7.8 ± 2.6).
- In the validation cohort, successful angiographic reperfusion resulted in lower QRS scores than unsuccessful reperfusion (4.5 ± 3.1 vs 9.3 ± 3.4), with similar salvage observed whether treated within ≤3 hours (4.2 ± 2.8) or 3–6 hours (4.1 ± 2.1).
- Wide confidence intervals driven by substantial inter-individual variability precluded the accurate prediction of individual 48-hour QRS scores from presentation ST-segment area measurements.
Structured PICO
Does thrombolytic treatment reduce evolved infarct size assessed by QRS score in patients with anterior myocardial infarction?
PPopulation90 patients admitted with anterior myocardial infarction within 6 h of onset (Group 1 n=35, Group 2 n=33, third set n=22).
IInterventionThrombolytic treatment either by intracoronary (streptokinase) or intravenous route (anistreplase).
CComparatorAnalgesia only.
OOutcomeEvolved infarct size at 48 h assessed by a QRS scoring system.surrogate
Thrombolytic treatment within 6 hours of anterior myocardial infarction significantly reduces evolved infarct size as assessed by QRS scoring, though individual prediction from initial ST elevation is limited by high variability.
Limitations
- Wide confidence intervals caused by inter-individual variability precluded an accurate prediction of the QRS score in an individual from the sigma ST area at time of presentation.