PARIS – Intra-aortic counterpulsation balloon therapy during percutaneous coronary intervention did not reduce infarct size in patients with ST-elevation myocardial infarction without shock in the multicenter, international CRISP-AMI trial.
The findings do not, however, close the door on this widely used therapy, Dr. Manesh Patel said at the annual congress of the European Society of Cardiology.
"Clinicians should continue to be vigilant about identifying patients who are at risk for rapid deterioration or hypertension that may still benefit from support, as seen with the crossover in this trial," he said at the meeting.
In all, 8.5% of patients randomized to percutaneous coronary intervention (PCI) alone crossed over to rescue intra-aortic balloon counterpulsation (IABC) in the CRISP-AMI (Counterpulsation to Reduce Infarct Size Pre-PCI Acute Myocardial Infarction) study.
Among all 337 patients in the trial, mean infarct size was 42% of the left ventricle in patients randomized to IABC prior to PCI and continued for at least 12 hours and 37.5% in the PCI-alone group (P = .06), said Dr. Patel of the Duke Clinical Research Institute in Durham, N.C.
In patients with proximal left anterior descending and thrombolysis in myocardial infarction flow scores of 0 or 1, the mean infarct size was 46.7% of the left ventricle vs. 42.3%, respectively (P = .11).
Invited discussant Dr. Kurt Huber, director of the department of medicine, cardiology, and emergency medicine at Wilhelminenspital in Vienna, said, "I’m sure that this method is still important for certain patient groups."
He noted that American Heart Association guidelines recommend IABC for patients in cardiogenic shock, with a 1B recommendation.
Moreover, despite missing statistical significance, hard clinical end points were lower in the IABC arm, Dr. Huber said.
At 6 months, three patients in the IABC plus PCI group had died vs. nine in the PCI-alone group (P = .12).
An exploratory composite end point of time to death, shock, or new or worsening heart failure also favored the counterpulsation therapy plus PCI group over the PCI-alone group (8 events vs. 21 events, P = .03).
There was, however, a nonsignificant increase in side effects, particularly vascular complications, Dr. Huber said.
At 30 days, major vascular complications occurred in seven patients in the IABC plus PCI group vs. only two in the PCI-alone group (P = .09.). Major bleeding or transfusion occurred in five patients vs. three patients, respectively, Dr. Patel reported.
Dr. Huber said other studies are needed to define which patients might benefit from IABC. He highlighted the only other prospective trial of IACP, the TACTICS trial, in which IAPC failed to offer a survival benefit when added to fibrinolysis for patients with MI who were hemodynamically unstable, but suggested a possible benefit for patients with the most severe heart failure or hypertension (J. Thromb. Thrombolysis 2005;19:33-9).
Session comoderator Dr. Christodoulos Stefanadis of Athens University Medical School said in an interview that it is still acceptable to use IACP in both stable and unstable patients, but agreed that other studies are needed to resolve the issue.
"For many years, we believe that the use of the intra-aortic pump is an effective means to reduce infarct size and to reduce the mortality rate, especially in patients with cardiogenic shock," he said.
"In unstable patients, I personally believe that the use of the intra-aortic pump remains effective, but the question is what happens in stable patients without low blood pressure or shock."
At baseline, CRISP-AMI patients were hemodynamically stable, with a median systolic blood pressure of 130 mm Hg in the IABC plus PCI group and 135 mm Hg in the PCI-alone patients.
The time required to insert the intra-aortic balloon added just 9 minutes to the procedure, making it unlikely that this derailed the potential benefits of counterpulsation therapy, Dr. Patel said in an interview.
The results of CRISP-AMI were simultaneously published online by JAMA (2011 Aug. 30 [doi:10.1001/jama.2011.1280]).
Dr. Patel reported receiving grant funding and travel reimbursement from the study sponsor Maquet (formerly Datascope).