In the late 1960's the technology of counter-pulsation by using an intra-aortic balloon pump (IABP) was introduced into clinical work. Based on the principle of diastolic inflation and systolic deflation, IABP counter-pulsation improves diastolic coronary artery blood flow and decreases left ventricular afterload. Up to the year 2009, 2012 respectively, the usage of an IABP in patients with ST-segment elevation myocardial infarction and cardiogenic shock was considered a class IC recommendation (reminder: levels of evidence).
Since then a couple of well conducted, larger trials have failed to show a positive impact of IABP especially on mortality. In regards of the most recent meta-analysis in JAMA we provide a short overview of the most important publications. It's interesting to see that the balloons undermining started with a meta-analysis and for the the time being ends with one.
The first notable hole in the ballon was caused by Sjauw et al.'s systematic review and meta-analysis in the European Heart Journal in 2009. Their pooled randomized data consisting of two separate meta-analyses did not support the use of an IABP in patients with high risk STEMI. They concluded that there is insufficient evidence endorsing the current guideline recommendation for the use of IABP therapy in the setting of STEMI complicated by cardiogenic shock.
This publication was one of the main reasons for the expert panel of the European Society of Cardiology to change the recommendation (ESC Guidelines 2012) to use an IABP in patients with STEMI from IC to IIB.
Stitch 2 and 3
In the same year 2012 Thiele et al. published their first IABP-SHOCK II results in the NEJM. Their
randomized, prospective, open-label, multicenter trial showed no reduction in the 30-day mortality compared to the best available medical therapy alone in patients with myocardial infarction-induced cardiogenic shock and planned early revascularization (PCI or CABG).
One year later the IABP-SHOCK II investigators published their final 12-months results in The Lancet. They came to the final conclusion that in patients undergoing early revascularization for myocardial infarction with cardiogenic shock, IABP did not reduce 12-month all-cause mortality.
Stitch no. 4
In 2013 Ranucci at al. presented the results of their single-center prospective randomized controlled trial looking at the usage of a preoperative IABP in high-risk patients undergoing surgical coronary revascularization. By looking at a total of 110 patients with an ejection fraction below 35% and no hemodynamic instability there was no improvement in outcome when inserting an IABP preoperatively.
Preliminary Final Stitch
So finally Ahmad and his team decided to assess IABP efficacy in acute myocardial infarction by performing an updated meta-analysis. Main outcome was 30-day mortality. They included 12 eligible RCTs randomizing 2123 patients and found no improvement in mortality among patients with acute myocardial infarction... regardless of whether patients had cardiogenic shock or not!
A look at another 15 eligible observational studies with a total of 15 530 patients showed basically conflicting results which was explained by the differences between studies in the balance of risk factors between IABP and non-IABP groups.
It seems that the IABP fails to show its assumed efficacy in patients with myocardial infarction and cardiogenic shock, especially when early revascularization (PCI or CABG) is available.
As a general consideration and also when no early revascularisation is available the use of another left-ventricular assist device like the Impella pump might prove to be a good and easy to use alternative (see blow).
Sjauw KD et al. Eur Heart J 30: 459-468
ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation. Eur Heart J 33: 2569-2619 OPEN ACCESS
Thiele et al. N Engl J Med 2012; 367:1287-1296 OPEN ACCESS
Thiele et al. The Lancet, Volume 382, Issue 9905, Pages 1638 – 1645
Crit Care Med. 2013 Nov;41(11):2476-83
JAMA Intern Med. Published online March 30, 2015
Short film on the principle of the Impella pump 2.5. Bare in mind that this device can actually be easily inserted in the environment of ICU and positioned by using transthoracic echo TTE.