August 24th, 2010

Questions About IABP During High-Risk PCI

CardioExchange welcomes Simon Redwood and Divaka Perera to discuss their randomized trial of routine intra-aortic balloon pump (IABP) insertion during high-risk PCI for the reduction of major adverse cardiac and cardiovascular events (MACCE) in patients with severe LV dysfunction and extensive coronary disease. Their study, which appears in the Journal of the American Medical Association, showed that, among 301 patients with LVEF < 30% and Jeopardy Score > 8/12, elective IABP did not reduce the incidence of MACCE. An intriguing observation was the difference in all-cause mortality at 6 months of 7.4% in the control group compared with 4.6% in the IABP group. IABP treatment was also associated with fewer major procedural complications but more bleeding complications.

Do you think that this study is sufficient to recommend that the routine use of IABP for patients undergoing high-risk PCI be abandoned? Should it be a Class III recommendation (that is, should not be used) in the next guidelines?

Simon Redwood: The take-home message certainly isn’t that the IABP has no role in the cath lab. What we have shown is that it doesn’t need to be used routinely in these patients (i.e., extensive coronary disease and poor LV function) undergoing elective angioplasty. However, there will still be some patients with very poor LV function and complex disease who will benefit from their use prophylactically — we only scored extent of coronary disease, not complexity. The SYNTAX score can classify complexity but was not available when we designed this trial.

All previous recommendations regarding IABP use have been based on registries. This is the first prospective randomized trial, and we hope will certainly help to revise the current guidelines. With a trial of this size we couldn’t perform multiple sub-analyses, but it appears that the patients requiring bailout IABP use were towards one end of the spectrum of our cohort (i.e., more extensive disease).

Finally, the investigators involved in this trial were all “high-volume” PCI operators with extensive experience in dealing with such “high-risk” patients. Although very speculative, if the trial had been done in low-volume centers by low-volume operators, the results may have been different!

As far as we know, this is the largest cohort of “ischaemic cardiomyopathy” patients undergoing PCI reported and, overall, the mortality is excellent, so we see it as a very positive trial for PCI!

Just to put that in perspective, only about 2% of the patients in SYNTAX had a EF of less than 30%!

Divaka Perera: I would echo Simon’s comments. I think the trial does definitively address the question of routine IABP insertion in patients with poor LV function and extensive coronary disease. What it doesn’t do is to allow us to clearly identify (prospectively) the important minority (nearly 1 in 8 in this study) who are going to need rescue IABP support during the case. Post-hoc analysis suggests that these were patients with virtually the whole myocardium subtended by diseased coronary arteries but the study was not powered to allow full multivariate analysis of this subgroup. As such, we would recommend a standby approach for such high-risk cases.

What do you think of the 6-month mortality difference between the groups? Although the difference is not significant, it is consistent with a large effect.

Simon Redwood: The 6-month mortality difference, although not significant, is certainly interesting and has prompted us to continue to follow these patients longer term to see if any “real” differences emerge. Again, highly speculative, it could be possible that there were small differences in LV function associated with the IABP that may translate to a difference in long-term outcome beyond 6 months. Note that our trial was not designed to be powered to look at this, but nevertheless, we will continue to follow the patients.

What will you say to those who point to the differences in the procedural complications?

Simon Redwood: The differences in procedural complications were largely hemodynamic issues, particularly hypotension, which highlights the importance of a standby approach in these patients and prompt IABP insertion at the earliest hint of emerging problems. I was quoted years ago as saying,” If you think of a balloon pump for more than a few seconds you should probably put one in.” Perhaps that could now be modified to include “…during the case!”

One Response to “Questions About IABP During High-Risk PCI”

  1. Sofya Baranova, MD says:

    Dear Sirs,
    Thank you for your investigation, we are highly interested in this topic.
    We have experience in IABP use during high-risk PCI in Moscow Cardiology Center, and we have an opinion that formal criteria for counterpulsation should be significally narrowed, for example, ejection fraction by itself in patients with severe disease of coronary arteries means not as much as complex examination of patients’ condition and patients’ haemodynamics. We are convinced, that In order to estimate real perspectives of IABP it’s needed to fix more concrete group of patients.
    For example an unstable patient with EF 30%, with serious signs of heart failure and large ischemia zone,is more “suitable” for counterpulsation than a patient in a stable condition with the same EF 30% in case of similar coronary aterostenosis.
    We are excited to know your point of view considering this problem.
    Faithfully yours,
    Sofya Baranova