Two recent trials question the ongoing use of intra-aortic balloon pumps: in patients with acute myocardial infarction with cardiogenic shock undergoing revascularisation(1), and patients with poor left ventricular function undergoing coronary artery bypass surgery(2).
Editorialists Krischan D Sjauw and Jan J Piek from the Netherlands make the following commentary(3) in reference to one of the studies:
Although the results of IABP-SHOCK II question the usefulness of IABP therapy in cardiogenic shock, there still might be an indication for initial stabilisation of severely compromised patients, especially in centres without facilities for early revascularisation, as an adjunct to thrombolytic therapy, or to allow transport to specialised tertiary centres.
So retrieval specialists like me may still be up in the night transferring patients with balloon pumps, but these studies suggest this should be restricted to those with cardiogenic shock pending corrective therapy (eg. revascularisation for AMI or surgery for acute mitral valvular dysfunction). Unless the ECMO team gets to them first, of course.
1. Intra-aortic balloon counterpulsation in acute myocardial infarction complicated by cardiogenic shock (IABP-SHOCK II): final 12 month results of a randomised, open-label trial
The Lancet, Volume 382, Issue 9905, Pages 1638 – 1645
BACKGROUND: In current international guidelines the recommendation for intra-aortic balloon pump (IABP) use has been downgraded in cardiogenic shock complicating acute myocardial infarction on the basis of registry data. In the largest randomised trial (IABP-SHOCK II), IABP support did not reduce 30 day mortality compared with control. However, previous trials in cardiogenic shock showed a mortality benefit only at extended follow-up. The present analysis therefore reports 6 and 12 month results.
METHODS: The IABP-SHOCK II trial was a randomised, open-label, multicentre trial. Patients with cardiogenic shock complicating acute myocardial infarction who were undergoing early revascularisation and optimum medical therapy were randomly assigned (1:1) to IABP versus control via a central web-based system. The primary efficacy endpoint was 30 day all-cause mortality, but 6 and 12 month follow-up was done in addition to quality-of-life assessment for all survivors with the Euroqol-5D questionnaire. A masked central committee adjudicated clinical outcomes. Patients and investigators were not masked to treatment allocation. Analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, NCT00491036.
FINDINGS: Between June 16, 2009, and March 3, 2012, 600 patients were assigned to IABP (n=301) or control (n=299). Of 595 patients completing 12 month follow-up, 155 (52%) of 299 patients in the IABP group and 152 (51%) of 296 patients in the control group had died (relative risk [RR] 1·01, 95% CI 0·86-1·18, p=0·91). There were no significant differences in reinfarction (RR 2·60, 95% CI 0·95-7·10, p=0·05), recurrent revascularisation (0·91, 0·58-1·41, p=0·77), or stroke (1·50, 0·25-8·84, p=1·00). For survivors, quality-of-life measures including mobility, self-care, usual activities, pain or discomfort, and anxiety or depression did not differ significantly between study groups.
INTERPRETATION: In patients undergoing early revascularisation for myocardial infarction complicated by cardiogenic shock, IABP did not reduce 12 month all-cause mortality.
2. A Randomized Controlled Trial of Preoperative Intra-Aortic Balloon Pump in Coronary Patients With Poor Left Ventricular Function Undergoing Coronary Artery Bypass Surgery
Crit Care Med. 2013 Nov;41(11):2476-83
BACKGROUND: Preoperative intra-aortic balloon pump use in high-risk patients undergoing surgical coronary revascularization is still a matter of debate. The objective of this study is to determine whether the preoperative use of an intra-aortic balloon pump improves the outcome after coronary operations in high-risk patients.
DESIGN: Single-center prospective randomized controlled trial.
SETTING: Tertiary cardiac surgery center, research hospital.
PATIENTS: One hundred ten subjects undergoing coronary operations, with a poor left ventricular ejection fraction (< 35%) and no hemodynamic instability.
Patients randomized to receive preincision intra-aortic balloon pump or no intervention.
MEASUREMENTS AND MAIN RESULTS: The primary outcome measurement was postoperative major morbidity rate, defined as one of prolonged mechanical ventilation, stroke, acute kidney injury, surgical revision, mediastinitis, and operative mortality. There was no difference in major morbidity rate (40% in intra-aortic balloon pump group and 31% in control group; odds ratio, 1.49 [95% CI, 0.68-3.33]). No differences were observed for cardiac index before and after the operation; at the arrival in the ICU, patients in the intra-aortic balloon pump group had a significantly (p = 0.01) lower mean systemic arterial pressure (80.1 ± 15.1 mm Hg) versus control group patients (89.2 ± 17.9 mm Hg). Fewer patients in the intra-aortic balloon pump group (24%) than those in the control group (44%) required dopamine infusion (p = 0.043).
CONCLUSIONS: This study demonstrates that in patients undergoing nonemergent coronary operations, with a stable hemodynamic profile and a left ventricular ejection fraction less than 35%, the preincision insertion of intra-aortic balloon pump does not result in a better outcome. Given the possible complications of intra-aortic balloon pump insertion, and the additional cost of the procedure, this approach is not justified.
3. Is the intra-aortic balloon pump leaking?