The goal of this study was to characterize determinants of
infarct size in the multicenter randomized
Counterpulsation to Reduce
Infarct Size Pre-PCI Acute
Myocardial Infarction (CRISP-AMI) trial. Contemporary determinants of
infarct size in patients presenting with acute anterior
myocardial infarction without
shock and undergoing percutaneous revascularization have been incompletely characterized. In CRISP-AMI, 337 patients with acute anterior
ST segment elevation myocardial infarction but without
cardiogenic shock at 30 sites in 9 countries were randomized to initiation of intra-aortic balloon
counterpulsation before primary
percutaneous coronary intervention versus standard of care. The primary outcome was
infarct size as measured by cardiac magnetic resonance imaging 3 to 5 days after
percutaneous coronary intervention. Of 337 randomized patients, complete periprocedural and
infarct size data were available in 250 patients (74%). After a comparison of baseline characteristics to ensure no significant differences, patients with missing data were excluded. Using multiple linear regression of 23 variables, time from symptom onset to first device (β = 0.022, p = 0.047) and preprocedural Thrombolysis In
Myocardial Infarction flow 0/1 (β = 15.28, p <0.001) were independent predictors of
infarct size.
Infarct size increased by 0.43% per 30 minutes in early reperfusion and by 0.63% every 30 minutes in late reperfusion. In conclusion, in patients with acute anterior ST elevation myocardial infraction without
cardiogenic shock, total ischemic time and preprocedural Thrombolysis In
Myocardial Infarction flow 0/1 were associated with increased
infarct size as determined by cardiac magnetic resonance imaging. These findings underscore the importance of systems of care aimed at reducing total ischemic time to open
infarct arteries.