Intra-aortic Balloon Pump (IABP) FAQs

1. How does IABP work?

Intra-aortic balloon pump (IABP) counterpulsation works by inflating the balloon during diastole and deflating it just before systole. This timing helps reduce the heart’s oxygen demand while increasing oxygen supply to the myocardium. The deflation before systole creates a vacuum effect that reduces afterload and improves forward blood flow from the left ventricle.13,14 However, adequate IABP support requires some degree of native left ventricular function to deliver meaningful benefit.¹ 

Although IABP inflation raises aortic pressure (AoP), this does not always translate into improved cardiac output or reduced pulmonary capillary wedge pressure (PCWP). For instance, in a HARVI hemodynamic simulation (harvi.online), IABP activation resulted in only a modest 0.4 L/min increase in cardiac output and a minimal decrease in PCWP. 

2. Is there a role for IABP in cardiogenic shock?

Initial IABP SHOCK II results

The Intra-aortic Balloon Pump in Cardiogenic Shock II (IABP-SHOCK II) trial, published in 2012, found that intra-aortic balloon counterpulsation did not significantly reduce 30-day mortality in patients with cardiogenic shock following acute myocardial infarction (AMI), even when early revascularization was planned.²

In this randomized, prospective, open-label, multicenter trial, 600 patients with cardiogenic shock following acute myocardial infarction (AMI) were assigned to either receive intra-aortic balloon pump (IABP) support, administered before or after PCI at the operator’s discretion, or no IABP support. The treatment plan was for all patients to receive the best available medical treatment according to guidelines and undergo early revascularization. Nearly all (95.8%) patients underwent primary PCI, with 3.5% undergoing immediate coronary artery bypass surgery (CABG) or initial PCI with subsequent CABG and 3.2% of patients receiving no revascularization.² 

The IABP-SHOCK II trial found no significant difference in the primary endpoint of 30-day all-cause mortality between the IABP and control groups. Furthermore, among patients who received IABP, there was no mortality difference between those who had the device inserted before PCI (13.4%) and those who received it after revascularization (86.6%).² 

Secondary outcomes, including bleeding, ischemic complications, stroke, time to hemodynamic stabilization, ICU length of stay, catecholamine dose and duration, and renal function, also showed no significant differences between the groups.  

IABP use did not lead to immediate improvements in blood pressure or heart rate, nor did it significantly affect markers of inflammation or tissue oxygenation, such as C-reactive protein or serum lactate levels.² 

Long-term 6-year IABP SHOCK II outcomes

Long-term 6-year outcomes of the IABP-SHOCK II trial demonstrate that IABP has no long-term effects on all-cause mortality. Follow-up was completed for 98.5% of the 600 patients initially enrolled in the trial. In addition to no difference in mortality, there were no differences in recurrent myocardial infarction, stroke, repeat revascularization, or rehospitalization for cardiac reasons. NYHA class and EuroQol 5D questionnaire measures also revealed no differences in survivor’s quality of life.³

3. What do clinical guidelines say about the use of IABP in cardiogenic shock?

In the 2025 ACC/AHA guidelines for the management of acute myocardial infarction (AMI), the routine use of intra-aortic balloon pump (IABP) in patients with cardiogenic shock has been reclassified as a Class III recommendation, indicating that the treatment is not effective and may be potentially harmful¹⁵. This update aligns North American guidance with longstanding European recommendations. IABP had already been classified as a Class III intervention in the 2017 European Society of Cardiology (ESC) guidelines, based on evidence from trials such as IABP-SHOCK II. 

The IABP-SHOCK II trial, along with its six-year follow-up data, showed no mortality benefit with routine IABP use in this population. In a 2019 editorial, Dr. Judith Hochman and colleagues emphasized that the data supported a limited role for IABP in managing AMI with cardiogenic shock, urging North American societies to update their recommendations accordingly. The CRISP-AMI trial, also cited in the ESC guidelines, further reinforced the limited utility of IABP by demonstrating no reduction in infarct size among patients with anterior ST-segment elevation myocardial infarction (STEMI) without shock who received IABP support before percutaneous coronary intervention (PCI). ^4,5

Learn more about the 2025 ACC/AHA recommendations for MCS in patients with ACS and cardiogenic shock.

4. Is there a role for IABP in Protected PCI?

BCIS-1 study

Results from BCIS-1 (Balloon Pump-Assisted Coronary Intervention Study) demonstrated that elective IABP insertion did not reduce the incidence of major adverse cardiac and cardiovascular events (MACCE) following PCI. The authors concluded that these results do not support a strategy of routine elective IABP insertion before high-risk PCI.⁶ 

BCIS-1, the first randomized controlled trial to assess the efficacy and safety of elective IABP use in patients undergoing high-risk PCI, was a prospective, open, multicenter, randomized controlled trial conducted in 17 tertiary referral cardiac centers in the UK between December 2005 and January 2009. 

The study randomized 301 patients with severe left ventricular dysfunction and extensive coronary disease to undergo elective IABP insertion before PCI or to undergo PCI without planned IABP support.

The trial aimed to evaluate whether the routine use of intra-aortic balloon pump (IABP) before PCI could reduce major adverse cardiac and cerebrovascular events (MACCE) in patients with severe left ventricular dysfunction and extensive coronary artery disease. MACCE was defined as a composite of death, acute myocardial infarction (AMI), cerebrovascular events, or the need for additional revascularization via PCI or CABG, assessed at hospital discharge (up to 28 days). 

Secondary endpoints included all-cause mortality at 6 months, major procedural complications (such as prolonged hypotension, ventricular tachycardia or fibrillation requiring defibrillation, or cardiorespiratory arrest requiring ventilatory support), as well as bleeding and access-site complications.⁶

In addition to demonstrating no difference in MACCE at hospital discharge, the study results showed that elective IABP use, while associated with significantly fewer procedural complications, was also associated with more minor bleeding and more access-site complications than PCI performed without planned use of IABP. The authors write, “These results do not support a strategy of prophylactic placement of an intra-aortic balloon catheter during PCI in all patients with severe left ventricular dysfunction and a high myocardial Jeopardy Score.” ⁶

PROTECT II Randomized Controlled Trial

The PROTECT II randomized controlled trial showed that patients treated with the Impella 2.5® device had a significantly lower rate of major adverse events (MAE) at 90 days compared to those treated with an intra-aortic balloon pump (IABP)—40.0% vs. 51.0% (P=0.023), representing a 22% relative risk reduction.⁷

In the high-risk PCI population, Impella use was also associated with a 29% reduction in major adverse cardiac and cerebrovascular events (MACCE) at 90 days—22% in the Impella group compared to 31% in the IABP group (P=0.034).⁸ Notably, most adverse events occurred after hospital discharge.⁸

PROTECT II was a prospective, multicenter, randomized, controlled trial of hemodynamic support with Impella 2.5 versus intra-aortic balloon pump (IABP) in patients undergoing nonemergent high-risk percutaneous coronary intervention (PCI). The study was designed to assess whether an Impella-supported high-risk percutaneous revascularization strategy would result in better outcomes than a revascularization strategy with IABP support.¹ 

5. What do key opinion leaders have to say about IABP use? 

KOL: Jacob Møller MD, PhD 

Jacob Møller MD, PhD, who recently published a paper on contemporary trends in the use of MCS in patients with AMI cardiogenic shock, ⁹ explains that in Denmark after publication of the IABP-SHOCK II results in 2012, “more or less overnight… we stopped using the balloon pump for the indication of shock and AMI.” Dr. Møller is an intensivist at Copenhagen University Hospital.

KOL: Giuseppe Tarantini, MD, PhD, FESC 

Describing data from several IABP studies, Giuseppe Tarantini, MD, PhD, FESC, notes, “We did not observe any benefits with intra-aortic balloon pump and unloading with balloon pump even though you go pre-PCI.” Highlighting IABP data from various types of patients from BCIS-1 RCT,⁶ CRISP-AMI,5 cVAD Study,¹⁰ IABP-SHOCK II,¹¹ and a meta-analysis in ECMO patients,¹² Dr. Tarantini explains, “you won’t see any significant advantage in terms of MACCE, infarct size, survival, and so on.” Dr. Tarantini is professor and director of interventional cardiology at the University of Padua in Italy and president of the Italian Society of Interventional Cardiology-GISE. 

6. Is there a role for IABP in Heart Failure Cardiogenic Shock? 

According to the ALTSHOCK-2 randomized controlled trial (RCT), the early use of IABP does not improve outcomes in patients with heart failure-related cardiogenic shock (HFCS) when compared to standard vasoactive therapy. 

Key Findings from ALTSHOCK-2 include: 

• No survival benefit: Early IABP support did not improve 60-day survival or the likelihood of successful bridging to heart replacement therapy (HRT) compared to standard care. 
• Neutral results across subgroups: The neutral outcome persisted even in subgroup analyses that accounted for variables such as age, sex, mean arterial pressure (MAP), lactate, ejection fraction, and SCAI stage at admission. 

There were safety concerns related to higher rates of bleeding (17% vs. 8.3%) and vascular complications (7.5% vs. 0%). As IABP failed to show benefits in other RCTs, this led to the re-classfication of routine IABP use as AMI-CS as Class III: No Benefit.  

Conversely, alternative MCS options such as Impella 5.5 show potential as primary therapy in HFCS associated with improved survival and native heart recovery. The relative survival rate with Impella 5.5 as primary therapy improved by 33%. ¹⁶  

The use of Advanced MCS (Impella CP/2.5 and ECMO) in patients with non ischemic cardiogenic shock was associated with a 24% relative risk reduction in 30-day mortality.¹⁷ 

The ALTSHOCK-2 trial and accumulated clinical evidence challenge the routine use of IABP in heart failure-related cardiogenic shock. When medical management fails, selecting advanced mechanical circulatory support tailored to the patient’s early trajectory appears more impactful in improving outcomes.