NEW YORK (Reuters Health) – Intra-aortic balloon counterpulsation (IABC) to augment blood flow before and for 12 hours after percutaneous coronary intervention (PCI) does not reduce infarct size or improve clinical outcomes in patients with acute anterior wall ST-segment elevation myocardial infarction (STEMI).
That’s according to findings from the Counterpulsation to Reduce Infarct Size Pre-PCI Acute Myocardial Infarction (CRISP AMI) study published online August 30 in the Journal of the American Medical Association to coincide with a presentation at the European Society of Cardiology Congress.
“Intra-aortic counterpulsation has been around for years; it is a common practice for patients in cardiogenic shock with failing hearts,” Dr. Manesh Patel, of the Duke Clinical Research Institute at Duke University in Durham, North Carolina, noted in an e-mail to Reuters Health.
The technique involves inserting a balloon into the aorta of patients to inflate during the diastolic and deflate during the systolic phase of the heart contraction. This “reduces the workload of the heart and increases the coronary perfusion pressure helping blood return to the heart,” Dr. Patel explained.
Some observational studies have suggested a possible clinical benefit in patients with high-risk STEMI receiving IABC prior to reperfusion with PCI and stenting. The CRISP AMI study was designed to further investigate this possibility.
A total of 337 patients with acute anterior STEMI without cardiogenic shock participated in the trial conducted at 30 sites in 9 countries from June 2009 to February 2011.
A total of 161 patients were randomized to IABC prior to primary PCI, and continuing for at least 12 hours (IABC plus PCI) and 176 to primary PCI alone.
No Clear Cut Benefit With IABC
According to the investigators, the mean infarct size (the primary outcome measured by cardiac MRI a median of 4 days after symptom onset) did not differ significantly between the groups. It was 42.1% of the left ventricle in patients in the IABC plus PCI group and 37.5% of the left ventricle in those in the PCI alone group.
There were also no noteworthy differences in higher-risk patients who had proximal left anterior descending Thrombolysis in Myocardial Infarction (TIMI) flow scores of 0 or 1; mean infarct sizes in this subset were 46.7% with IABC and 42.3% without.
At 30 days, there were no significant between-group differences in major vascular complications and major bleeding or transfusions. By 6 months, 3 patients (1.9%) in the IABC plus PCI group and 9 patients (5.2%) in the PCI alone group had died.
Unlike patients with cardiogenic shock for whom guidelines recommend IABC, patients with high-risk anterior STEMI without shock do not seem to benefit from early routine use of IABC.
The investigators note, however, that 8.5% of patients in the PCI alone group did cross over to rescue IABC therapy. “These findings support a standby strategy (rather than routine use) of IABC during primary PCI in high-risk anterior or STEMI patients,” they say.
In comments to Reuters Health, Dr. Patel said, “Clinicians should continue with guideline based care – that is opening the occluded heart artery in patients without cardiogenic shock and acute heart attack as fast as possible, with clinical vigilance for identifying patients that might be deteriorating and would benefit from this device.”
Message from CRISP AMI Clear
In a linked commentary, Dr. Gjin Ndrepepa and Dr. Adnan Kastrati from Deutsches Herzzentrum, Technische Universität, Munich, Germany, note that the issue of using IABC during high-risk PCI procedures or in STEMI “remains controversial” and the CRISP AMI study “helps to clarify this controversy.”
“The clear-cut message from the CRISP AMI trial,” they write, “is that among patients with STEMI without cardiogenic shock, the routine use of IABC neither reduces infarct size nor improves clinical outcome; accordingly, use of this device should be discouraged in these patients.”
“Other research avenues for the treatment of patients with STEMI remain attractive. Organizational efforts to increase the availability of primary PCI and reduce ischemia time remain of paramount clinical importance,” Drs. Ndrepepa and Kastrati conclude.
JAMA 2011. Published online August 30, 2011.