Aborted myocardial infarction in patients with ST-segment elevation: insights from the Assessment of the Safety and Efficacy of a New Thrombolytic Regimen-3 Trial Electrocardiographic Substudy.
OBJECTIVE
The investigators undertook a systematic, comprehensive analysis of the therapeutic response and clinical outcomes of reperfusion therapy for acute ST-segment elevation myocardial infarction (STEMI) in 5,470 patients from the Assessment of the Safety and Efficacy of a New Thrombolytic Regimen (ASSENT)-3 trial.


BACKGROUND
Prompt effective reperfusion therapy for acute STEMI may attenuate major myocardial necrosis.


METHODS
We prospectively collected sequential electrocardiographs and clinical data. Aborted myocardial infarction (MI) was defined as maximal creatine kinase < or =2x upper limit of normal coupled with typical evolutionary electrocardiographic changes.


RESULTS
Of the patients, 727 (13.3%) had an aborted MI, with the highest frequency (25%) occurring in patients treated <1 h after symptom onset. As compared with MI patients, patients with aborted MI more often had complete ST-segment resolution at 60 min (56.3% vs. 30.2%, p < 0.001) and 180 min (61.5% vs. 53%, p < 0.001); they also had smaller infarct sizes based on QRS score at discharge (2.37 vs. 4.62, p <0.001). Mortality in aborted MI patients compared with those who had true MI was 3.9% versus 4.6% at 30-day and 7.0% versus 7.4% at 1-year. The baseline-adjusted mortality was significantly lower in patients with aborted MI (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.63 to 0.92, p = 0.005 for 30-day and OR 0.70, 95% CI 0.50 to 0.98, p = 0.035 for one year). A very low-risk subset was identified with > or =70% ST-segment resolution at 60 min whose 30-day and 1-year mortality was 1.0% and 2.7%, respectively, compared with 5.9% and 9.3% in aborted MI patients with <70% ST-segment resolution at 60 min (all p < or = 0.002).


CONCLUSIONS
Prompt fibrinolytic treatment improved the likelihood of aborted MI. The subgroup with complete 60-min ST-segment resolution had the best clinical outcomes.
Taher
Taha
T
University of Alberta, Edmonton, Alberta, Canada.
Fu
Yuling
Y
Wagner
Galen S
GS
Goodman
Shaun G
SG
Fresco
Claudio
C
Granger
Christopher B
CB
Wallentin
Lars
L
van de Werf
Frans
F
Verheugt
Freek
F
Armstrong
Paul W
PW
D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D015415:Biomarkers / Q000097:blood; D001026:Coronary Artery Bypass; D003402:Creatine Kinase / Q000097:blood; D004562:Electrocardiography; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use*; D006329:Heart Conduction System / Q000187:drug effects / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000628:therapy*; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology; D011446:Prospective Studies; D000077785:Tenecteplase; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use; D016896:Treatment Outcome
D015415:Biomarkers; D005343:Fibrinolytic Agents; D003402:Creatine Kinase; D010959:Tissue Plasminogen Activator; D000077785:Tenecteplase