Early IABP Use is Not Any Better Than Medication in Treating Cardiogenic Shock

Compared with standard medical care, early use of a temporary intra-aortic balloon pump (IABP) to support heart function in patients who are critically ill with cardiogenic shock caused by heart failure does not improve 60-day survival or enable more patients to successfully transition to long-term treatment, according to clinical research published in the Journal of the American College of Cardiology (JACC). Organizers stopped trial early when an independent physician monitoring group concluded the device offered no additional benefit to patients.

“Results from the early use of an intra-aortic balloon pump were comparable, but not superior to standard medical care and were not associated with improved survival or successful transition to a more permanent heart replacement therapy,” said Alice Sacco, M.D., a physician in the Cardiac Intensive Care Unit at Niguarda Metropolitan Hospital in Milan and a co-principal investigator on the study.

Cardiogenic shock is a life-threatening medical emergency that occurs when the heart cannot pump enough blood and oxygen to the brain and other vital organs. It may be caused by a heart attack or by another problem with the heart such as heart failure. Cardiogenic shock must be treated quickly to avoid organ failure, brain injury, or death. Long-term treatment may be a heart transplant or a permanently implanted ventricular assist device that helps the heart’s main pumping chamber pump blood to the body.

The IABP is used as a temporary measure to help the heart pump blood until either the patient receives longer-term treatment or the patient’s heart recovers enough to function without support. A balloon placed in the aorta (the body’s main artery), using a catheter (a long, thin tube), inflates when the heart is resting between heartbeats and deflates when the heart is pumping.

Developed in the 1960s, an IABP was the first device to provide temporary mechanical heart support in cardiogenic shock patients, Sacco said. Although other such devices have been developed more recently, the IABP remains popular because it is easy to use, less invasive, and less costly than other devices, and is less likely than similar devices to cause blood clots or other problems with blood flow, she said.

However, multiple studies have shown that heart attack-induced cardiogenic shock patients who received an IABP fared no better than those treated with medications that improve blood flow, Sacco said. In 2023, European Society of Cardiology guidelines recommended against routine IABP use in patients with cardiogenic shock resulting from a heart attack.

The Altshock-2 trial was conducted to determine whether—compared with standard medical therapy—an IABP would help heart failure-generated cardiogenic shock patients survive and transition to a heart transplant or a ventricular assist device, Sacco said.

The trial enrolled 101 patients at five medical centers in Italy. The subjects’ median age was 60 years and 80% were men, reflecting the fact that men are more likely than women to experience cardiogenic shock, Sacco said. All patients were hospitalized and critically ill with heart failure. According to Sacco, more than 90% had an implanted device to treat a heartbeat that was either too fast or too slow; 77% were taking medication to prevent blood clots; 70% had fluid buildup in the body due to right ventricle failure; and approximately 66% had inadequate blood pressure and blood flow to the body’s organs and tissues.

Trial organizers randomly assigned patients to treatment either with an IABP or with medications to regulate their heartbeat and improve the heart’s pumping ability (standard care). The trial’s primary endpoint was the percentage of patients who survived for 60 days and received long-term treatment for their heart failure (a heart transplant or permanently implanted ventricular assist device) or whose heart function improved or stabilized to the point that it no longer needed external support. Secondary endpoints included the intensity of treatment for heart failure and low blood pressure, the degree of organ failure patients experienced, and adverse events.

The trial design had called for enrolling 200 patients and for an independent physician team monitoring the trial to conduct an interim analysis after follow-up of the first 100 patients was completed. This analysis found that 43 patients (81%) in the IABP group and 36 (75%) in the standard-care group achieved the primary endpoint, a difference that was not statistically significant. Twenty-one patients (39.6%) in the IABP group and 16 (33%) in the standard-care group received a heart transplant or a permanently implanted ventricular assist device, also a non-statistically significant difference. Between-group differences in the secondary endpoints were also not statistically significant.

The independent physicians concluded the IABP was not providing patients with any meaningful benefit compared with standard care. They also determined it was unlikely that more patients in the IABP group than the standard-care group would achieve the primary endpoint even if the trial reached its enrollment goal. In response to the physicians’ unanimous recommendation, the trial ended early in October 2024.

“This was the largest trial designed to enroll patients with cardiogenic shock due to heart failure to assess the hypothesis that early intervention with the IABP would improve patient survival compared with standard care,” Sacco said. “These results show that early IABP use should not be the default approach to temporary mechanical support of the heart.”

The study has several limitations, Sacco said. Cardiogenic shock associated with heart failure may have a variety of underlying causes, which may affect how patients respond to IABP treatment. Managing IABP patients was not standardized at the study hospitals, and the trial design lacked guidelines for optimizing IABP function.  

The study was funded by an unrestricted grant from Getinge Global USA, manufacturer of one of the intra-aortic balloon pumps used in the trial.