Although door-to-balloon times have declined over the last few years, mortality rates from acute ST-elevation myocardial infarction (STEMI) have not improved. One proposed method to counteract this has been the routine use of intra-aortic balloon counter pulsation (IABC) during primary PCI; animal studies have suggested a reduction in infarct size, and a possible clinical benefit has been shown in some previous studies.
The CRISP AMI (Counterpulsation to Reduce Infarct Size Pre-PCI Acute Myocardial Infarction) trial was a large randomised study that aimed to determine if IABC prior to primary PCI could reduce infarct size; IABC treatment was continued for a minimum of 12 hours following the procedure. Patients in the standard care group of the trial received primary PCI without planned IABC support. The main outcome measure was infarct size, expressed as a percentage of left ventricular mass as assessed by cardiac MRI performed between 3 and 5 days post PCI.
337 patients with acute anterior STEMI, none of whom were in cardiogenic shock, were recruited. 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% vs 37.5%). At 30 days, there were no significant differences between the IABC plus PCI group and the PCI alone group for a number of clinical secondary endpoints, including major bleeding or transfusions (n = 5 vs n = 3 P = .49). At 6 months, 3 patients in the IABC plus PCI group and 9 patients in the PCI alone group had died (P = .12).
The routine use of IABC in patients undergoing primary PCI for STEMI did not lead to a reduction in infarct size. Clinical outcomes did not differ significantly at six months. However, IABC remains suitable for patients in cardiogenic shock.
- Patel, MR, Smalling RW, Thiele H, et al. Intra-aortic balloon counterpulsation and infarct size in patients with acute anterior myocardial infarction without shock: The CRISP AMI randomized trial. JAMA 2011; DOI:10.1001/jama.2011.1280.