Usefulness of IABP Questioned in MI Patients with Cardiogenic Shock

AMSTERDAM, The Netherlands— In patients undergoing early revascularization for myocardial infarction (MI) complicated by cardiogenic shock, use of an intra-aortic balloon pump (IABP) does not reduce all-cause mortality at 1 year, according to results presented on September 3, 2013, at the European Society of Cardiology (ESC) Congress and simultaneously published in the Lancet.

For the 37-center IABP-SHOCK (Intra-aortic Balloon Pump in Cardiogenic Shock) II trial, Holger Thiele, MD, of the University of Leipzig-Heart Center (Leipzig, Germany), and colleagues randomized 600 patients with AMI and cardiogenic shock who were expected to undergo early revascularization to receive optimal medical therapy with (n = 301) or without (n = 299) IABP between June 2009 and March 2012.

Thirty-day data, published in the New England Journal of Medicine in October 2012, demonstrated safety but showed equivalent mortality.

No Net Benefit with IABP

Of 595 patients completing 12-month follow-up, there were no differences by IABP implantation in mortality, recurrent revascularization, stroke, repeat PCI, or CABG. There was a strong trend toward more reinfarction in the IABP group (table 1).

Table 1. Clinical Outcomes at 1 Year

 

IABP
(n = 299)

Controls
(n = 296)

RR (95% CI)

P Value

All-Cause Mortality

51.8%

51.4%

1.01 (0.86-1.18)

0.91

CV Mortality

50.2%

50.0%

1.00 (0.85-1.18)

0.97

Reinfarction

9.0%

3.5%

2.60 (0.95-7.10)

0.05

Stroke

2.1%

1.4%

1.50 (0.25-8.84)

1.00

Repeat Revascularization

20.1%

22.2%

0.91 (0.58-1.41)

0.77

Repeat PCI

15.3%

17.4%

0.88 (0.52-1.49)

0.63

CABG

4.9%

4.9%

1.00 (0.36-2.78)

1.00

 
Multivariate analysis found several independent predictors of 12-month mortality including age, history of stroke, and baseline serum lactate (P < 0.001 for all). IABP support and time from angina or shock onset to randomization were not predictive of survival.

As for quality of life, there were no differences between the study arms at 1 year as per the EuroQol 5D survey in:

  • Mobility: P = 0.10
  • Self-care: P = 0.12
  • Usual Activities: P = 0.17
  • Pain/Discomfort: P = 0.08
  • Anxiety/Depression: P = 0.24

Guideline Downgrade Affirmed

Discussant Jan J. Piek, MD, PhD, of the University of Amsterdam (Amsterdam, The Netherlands), congratulated the researchers on conducting a study on a “really complex cohort of patients.”

He said IABP-SHOCK II endorses the recent downgrading of IABP use in both the American Heart Association/American College of Cardiology (AHA/ACC) and the ESC guidelines. The therapy went from a class I (IB for AHA/ACC and IC for ESC) to a class II (IIB for AHA/ACC and IIC for ESC) recommendation for this indication.

In an editorial accompanying the study, Dr. Piek and coauthor Krischan D. Sjauw, MD, also of the University of Amsterdam, write that “although the results of IABP-SHOCK II question the usefulness of IABP therapy in cardiogenic shock, there still might be an indication for initial stabilization of severely compromised patients, especially in centers without facilities for early revascularization, as an adjunct to thrombolytic therapy, or to allow transport to specialized tertiary centers.”

‘Huge Challenge’ Remains

But “we are still left with a huge challenge,” Dr. Piek said at the ESC Congress, adding that mortality remains high despite measures taken in the past decade. The use of more potent assist devices might help to fix this, he suggested.

Serum lactate might also be a great marker to use to predict high-risk patients since “you can easily get it directly after admission,” Dr. Thiele suggested. “We might need to adopt our treatment according to these parameters.”

Future research into pharmacological therapy capable of counteracting hemodynamic deterioration and systemic inflammatory response is warranted, Drs. Sjauw and Piek write in the editorial. “This research includes optimizing the strategy for use of inotropic drugs and vasopressors. Recent novel insight into the role of the massive release of monocytes in the systemic inflammatory response after acute MI might also lead to new therapeutic options in cardiogenic shock (ie, specific β-receptor blockers),” they conclude.

Study Details

Median age was 70 years, and 69% were male. About half (45%) underwent cardiopulmonary resuscitation before randomization, 77% had multivessel disease, and median LVEF was 35%.

Among controls, 10% subsequently underwent IABP insertion, most within the first 24 hours of randomization. However, 4.3% of patients assigned to an IABP did not receive the device, in many instances because the patient had died. Balloon insertion occurred before or immediately after revascularization, which was PCI in 95.8% of patients. Median duration of IABP support was 3.0 days (interquartile range, 2.0-4.0 days).

 


Sources:
1. Thiele H, Zeymer U, Neumann F-J, et al. Intra-aortic balloon counterpulsation in acute myocardial infarction complicated by cardiogenic shock (IABP-SHOCK II): Final 12 month results of a randomized, open-label trial. Lancet. 2013:Epub ahead of print.

2. Sjauw KD, Piek JJ. Is the intra-aortic balloon pump leaking? Lancet. 2013:Epub ahead of print.

 

 

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Disclosures
  • IABP-SHOCK II was funded by Maquet Cardiopulmonary and Teleflex Medical.
  • Dr. Thiele reports receiving funding from Lilly, Maquet Cardiopulmonary, Teleflex Medical, and Terumo; serving as a consultant to Lilly and Maquet Cardiopulmonary; and receiving speaker honoraria from AstraZeneca, Boehringer Ingelheim, Daiichi Sankyo, Lilly, Maquet Cardiopulmonary, and The Medicines Company.
  • Dr. Piek reports serving on the medical advisory board of Abbott Vascular and as a consultant to Miracor.
  • Dr. Sjauw reports no relevant conflicts of interest.

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