Intra-Aortic Balloon Counterpulsation and Infarct Size in Patients With Acute Anterior Myocardial Infarction Without Shock: The CRISP AMI Randomized Trial
What is the effect of routine intra-aortic balloon counterpulsation (IABC) placement prior to reperfusion in patients with anterior ST-segment elevation myocardial infarction (STEMI) without shock on myocardial infarct size?
An open, multicenter, randomized, controlled trial, the Counterpulsation to Reduce Infarct Size Pre-PCI Acute Myocardial Infarction (CRISP AMI) included 337 patients with acute anterior STEMI, but without cardiogenic shock, at 30 sites in nine countries from June 2009 through February 2011. Initiation of IABC before primary percutaneous coronary intervention (PCI) and continuation for at least 12 hours (IABC plus PCI) was compared with primary PCI alone. The main outcome measure was infarct size, expressed as a percentage of left ventricular (LV) mass and measured by cardiac magnetic resonance imaging (CMR) performed 3-5 days after PCI. Secondary endpoints included all-cause death at 6 months, and vascular complications and major bleeding at 30 days. Multiple imputations were performed for missing infarct size data. For the primary endpoint of infarct size measured by CMR, the null hypothesis of equal infarct size between the IABC plus PCI group and the PCI alone group was tested using the t test.
The median time from first contact to first coronary device was 77 minutes (interquartile range, 53-114 minutes) for the IABC plus PCI group versus 68 minutes (interquartile range, 40-100 minutes) for the PCI alone group (p = 0.04). The mean infarct size was not significantly different between the patients in the IABC plus PCI group and in the PCI alone group (42.1%; 95% confidence interval [CI], 38.7-45.6% vs. 37.5%; 95% CI, 34.3-40.8%, respectively; difference of 4.6%; 95% CI, −0.2% to 9.4%; p = 0.06; imputed difference of 4.5%; 95% CI, −0.3% to 9.3%; p = 0.07) and in patients with proximal left anterior descending Thrombolysis In Myocardial Infarction flow scores of 0 or 1 (46.7%; 95% CI, 42.8-50.6% vs. 42.3%; 95% CI, 38.6-45.9%, respectively; difference of 4.4%; 95% CI, −1.0% to 9.7%; p = 0.11; imputed difference of 4.8%; 95% CI, −0.6% to 10.1%; p = 0.08). At 30 days, there were no significant differences between the IABC plus PCI group and the PCI alone group for major vascular complications (n = 7; 4.3%; 95% CI, 1.8-8.8% vs. n = 2; 1.1%; 95% CI, 0.1-4.0%, respectively; p = 0.09) and major bleeding or transfusions (n = 5; 3.1%; 95% CI, 1.0-7.1% vs. n = 3; 1.7%; 95% CI, 0.4-4.9%; p = 0.49). By 6 months, three patients (1.9%; 95% CI, 0.6-5.7%) in the IABC plus PCI group and nine patients (5.2%; 95% CI, 2.7-9.7%) in the PCI alone group had died (p = 0.12).
The authors concluded that among patients with acute anterior STEMI without shock, IABC plus primary PCI compared with PCI alone did not result in reduced infarct size.
The principal finding from this study was that IABC inserted prior to primary PCI and continued for at least 12 hours after PCI did not reduce myocardial infarct size, as measured by CMR. The composite of death, shock, or heart failure at 6 months was not significantly different between the two groups, but seemed to favor the IABC plus PCI group, highlighting the potential effect of the early risk with the PCI alone group. Clinicians should continue to be vigilant about identifying patients who are at risk for rapid deterioration, and who may benefit from IABC (i.e., a standby strategy rather than routinely using an IABC during primary PCI in high-risk anterior STEMI patients).
Clinical Topics: Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Aortic Surgery, Cardiac Surgery and Heart Failure, Acute Heart Failure, Mechanical Circulatory Support , Interventions and Imaging, Magnetic Resonance Imaging
Keywords: Outcome Assessment (Health Care), Shock, Cardiogenic, Myocardial Infarction, Heart Failure, Counterpulsation, Magnetic Resonance Imaging, Percutaneous Coronary Intervention
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