Permanent damage to heart muscle was not reduced when intra-aortic balloon counter-pulsation procedure was used to increase pre- and post-bloodflow after a percutaneous coronary intervention among patients with certain types of heart attacks, researchers reported in JAMA (Journal of the American Medical Association). Examples of percutaneous coronary intervention include stent placement for widening narrowed coronary arteries or balloon angioplasty.

As background information, the authors explained:

“Patients with acute STEMI [ST-segment elevation myocardial infarction – a certain pattern on an electrocardiogram following a heart attack], representing 30 percent to 45 percent of approximately 1.5 million hospitalizations for acute coronary syndromes annually in the United States, are still at substantial acute mortality risk with 1-year mortality estimated to be between 6 percent and 15 percent. This may be related to micro-vascular obstruction resulting in no re-flow at the time of mechanical reperfusion and infarct [heart muscle damage] expansion over time.”

By using a balloon in the aorta, intra-aortic balloon counter-pulsation (IABC) coronary blood flow is mechanically increased. According to some observational studies in the U.S., there may be a possible clinical benefit in patients with high-risk STEMI receiving IABC before reperfusion with PCI and stenting with increased clinical use at an early stage.

A randomized, controlled trial was conducted by Manesh R. Patel, M.D., of the Duke Clinical Research Institute, Duke University Medical Center, in Durham, N.C., and his colleagues to assess if IABC inserted prior to primary PCI compared with primary PCI alone (standard of care) could reduce infarct size in patients with acute anterior (front part of heart) STEMI without cardiogenic shock (shock caused by heart failure).

The counter-pulsation to reduce infarct size pre-PCI acute myocardial infarction (CRISP AMI) trial was conducted on 337 patients at 30 sites in 9 countries between June 2009 and February 2011. One group of participants randomly received IABC prior to primary PCI, and IABC was continued for at least 12 hours (IABC plus PCI), another group were administered with primary PCI alone. Infarct size, defined as a percentage of left ventricular (LV) mass and measured by cardiac magnetic resonance imaging (MRI) was used as the primary measured outcome with secondary outcomes including all-cause death at 6 months and vascular complications and major bleeding at 30 days.

According to the findings, the average infarct size was similar between patients in the IABC plus PCI group (42.1%) and the PCI alone group (37.5 %). In higher-risk patients with other certain cardiac characteristics (proximal left anterior descending Thrombolysis in Myocardial Infarction flow scores of 0 or 1), the findings were slightly higher in the IABC plus PCI group (46.7%) compared to 42.3% in the PCI alone group. Secondary cardiac MRI findings proved to be consistent with infarct size findings, including average micro-vascular obstruction of 6.8% for the IABC plus PCI group compared to 5.7% in the PCI alone group.

The authors commented:

“At 30 days, there were no significant differences between the IABC plus PCI group and the PCI alone group for major vascular complications and major bleeding or transfusions…By 6 months, 3 patients (1.9 percent) in the IABC plus PCI group and 9 patients (5.2 percent) in the PCI alone group had died.”

There was no significant difference between the two groups between the time to the composite end point of death, recurrent heart attack, or new or worsening heart failure.

According to the authors, patients with high-risk anterior STEMI without shock do not seem to acquire a reduction in infarct size from early routine use of IABC, unlike those with cardiogenic shock, for whom guidelines recommend intra-aortic counter-pulsation.

The authors concluded:

“Clinicians should continue to be vigilant about identifying patients who are at risk for rapid deterioration and who may benefit from counter-pulsation (as seen with the crossover in this trial). Future studies should be aimed at identifying the patient features associated with early deterioration. “These findings support a standby strategy (rather than routine use) of IABC during primary PCI in high-risk anterior STEMI patients.”

Written by Petra Rattue