Study finds no benefit of early IABP use in cardiogenic shock patients

Compared with standard medical care, early use of a temporary intra-aortic balloon pump (IABP) to support heart function in patients who were critically ill with cardiogenic shock caused by heart failure did not improve 60-day survival or enable more patients to successfully transition to long-term treatment, according to featured clinical research presented at the American College of Cardiology's Annual Scientific Session (ACC.25) and simultaneously published in JACC. The trial was stopped early when an independent monitoring group of physicians concluded that the device offered patients no additional benefit.

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."

Alice Sacco, MD, physician in the Cardiac Intensive Care Unit at Niguarda Metropolitan Hospital in Milan and 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 rest of the body.

The IABP is a device 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.

The IABP, developed in the 1960s, was the first device to provide temporary mechanical support to the heart in patients with cardiogenic shock, Sacco said. Although other such devices have been developed more recently, the IABP remains widely used 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 patients experiencing cardiogenic shock caused by a heart attack who were treated temporarily with an IABP fared no better than similar patients who were 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 due to a heart attack.

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

A total of 101 patients were enrolled in the trial at five medical centers in Italy. The patients' 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 of the 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 failure of the heart's right ventricle, which pumps blood to the lungs; and approximately 66% had inadequate blood pressure and blood flow to the body's organs and tissues.

Patients were randomly assigned 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 medical treatment of heart failure and low blood pressure, the degree of organ failure patients experienced and adverse events.

The trial design had called for enrolling a total of 200 patients and for an independent team of physicians 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 that the IABP was not providing patients with any meaningful benefit compared with standard care. They also determined that even if the trial reached its enrollment goal, it was unlikely that more patients in the IABP group than in the standard-care group would achieve the primary endpoint. 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. Management of the patients treated with an IABP was not standardized at the hospitals participating in the trial, and the study design lacked guidelines for optimizing IABP function.

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

This study was simultaneously published online in JACC at the time of presentation.