IABP-SHOCK II Trial
Details
IABP-SHOCK II is the definitive randomised trial of intra-aortic balloon counterpulsation in acute myocardial infarction complicated by cardiogenic shock undergoing early revascularisation. It compared IABP plus standard care with standard care alone and is the reason routine IABP is not recommended in AMI-CS despite continued widespread use. (sources/cardiogenic-shock-acc-2025, rating: very high) (sources/cardiogenic-shock-nejm-2026, rating: very high)
Key Facts
- n = 600, multicentre, randomised, open-label; AMI-CS with planned early revascularisation. (sources/cardiogenic-shock-acc-2025, rating: very high)
- No effect on 30-day all-cause mortality. (sources/cardiogenic-shock-nejm-2026, rating: very high)
- No benefit at 6-year follow-up — the null result is durable, not a timing artefact. (sources/cardiogenic-shock-acc-2025, rating: very high)
- Renal replacement therapy was used in 18% of trial patients, indicating the severity of the enrolled population. (sources/cardiogenic-shock-nejm-2026, rating: very high)
- IABP remains widely used because of ease of insertion, low cost and a favourable adverse-event profile, and European guidelines recommend it for mechanical complications (US guidelines do not). (sources/cardiogenic-shock-nejm-2026, rating: very high)
Contradictions / Open Questions
- Practice has not followed the evidence. The trial is neutral at 30 days and 6 years, yet IABP use remains common; the stated reasons are procedural familiarity and safety rather than demonstrated benefit. (sources/cardiogenic-shock-nejm-2026, rating: very high)
- The device may still have a niche in mechanical complications (e.g. ventricular septal rupture, acute mitral regurgitation), which were not the focus of the randomised comparison — this is a guideline extrapolation rather than a trial result. (sources/cardiogenic-shock-nejm-2026, rating: very high)
- Whether a higher-support or earlier-insertion strategy would differ is untested; the trial addressed routine use in unselected AMI-CS.
Connections
- Related to concepts/Cardiogenic-Shock — AMI-CS phenotype and management
- Related to concepts/Cardiogenic-Shock — position of IABP in the device hierarchy
- Related to entities/ECLS-SHOCK-Trial and entities/DanGer-Shock-Trial — the other pivotal tMCS trials
- Related to entities/Acute-Coronary-Syndrome — the enrolled population