BCIS-1 Published: Elective IABP Benefits High-Risk PCI Patients

Contrary to lackluster short-term results, elective intra-aortic balloon pump (IABP) therapy in high-risk patients receiving percutaneous coronary intervention (PCI) substantially reduces all-cause mortality at 5 years. However, the mechanism behind this benefit is unknown, according to a paper published online December 6, 2012, ahead of print in Circulation.

The findings, from the Balloon pump-assisted Coronary Intervention Study (BCIS-1), were previously presented in March 2012 at the American College of Cardiology/i2 Scientific Session in Chicago, IL.

For BCIS-1, Divaka Perera, MA, MD, of St. Thomas’ Hospital, King’s College London (London, United Kingdom), and colleagues enrolled 301 patients with multivessel coronary disease and severe left ventricular dysfunction (LVEF ≤ 30%) undergoing PCI. Patients were randomized to receive elective IABP support (n = 151) or no planned IABP (n = 150) at 17 centers in the United Kingdom between December 2005 and January 2009.

Death Risk Drops by a Third

One hundred deaths occurred in the BCIS-1 cohort: 18 within 6 months of randomization, 16 between 6 months and 1 year, and 66 after 1 year. The overall rate of all-cause mortality was 33%; 42 of 151 patients receiving elective IABP (28%) died, as did 58 of 150 patients receiving no IABP (39%).

At 5 years, Kaplan-Meier estimates indicate that IABP use reduced the risk of long-term mortality by approximately one-third (HR 0.64; 95% CI 0.42-0.96).

The current analysis used government databases in Wales, England, and Scotland to quantify long-term mortality in 100% of the original cohort up to a median of 51 months (interquartile range, 41-58 months).

As reported previously in the Journal of the American Medical Association (Perera D, et al. JAMA. 2010;304:867-874), both IABP strategies had similar results for the primary endpoint of MACCE (defined as death, MI, cerebrovascular event, or further revascularization at hospital discharge [capped at 28 days]) and its components. In particular, there was no difference in 6-month mortality (HR 0.61; 95% CI 0.24-1.62).

No Clear Explanation

Interpretation of the new data is complicated by several factors, the paper notes. Bailout IABP was required in 12% of patients initially assigned to no hemodynamic support. Moreover, it is impossible to ascertain cause of death.

Possible explanations include reductions in periprocedural ischemia and infarction, the investigators suggest.

However, a “potential confounding factor that needs to be considered when interpreting these mortality data is the possible influence of treatment assignment on the nature of revascularization carried out in the trial,” Dr. Perera and colleagues write. “In particular, is there any evidence that allocation of a patient to an elective IABP strategy may have given the interventional cardiologist increased confidence with which to undertake more extensive and possibly more complex revascularization?” No such evidence has been found, they add.

Taking the Long View

In an editorial accompanying the paper, John P. Vavalle, MD, MHS, and E. Magnus Ohman, MD, both of Duke University Medical Center (Durham, NC), comment, “Strikingly, . . . Kaplan-Meier curves for survival not only demonstrate a significant difference at 5 years but . . . appear to be continuing to diverge even at 5 years.”

Drs. Vavalle and Ohman point out that findings from BCIS-1 are consistent with those from the PROTECT-II trial. The latter found an advantage in terms of major adverse events at 90 days for high-risk PCI patients who received the Impella 2.5 left ventricular assist device (Abiomed, Danvers, MA) vs. IABP but not at the 30-day mark of the primary endpoint.

Despite the “neutral” primary findings of BCIS-1 and PROTECT-II, the long-term results “suggest that when more complete revascularization is desirable, these devices will offer the potential to improve outcomes with high-risk PCI,” the editorial concludes. Moreover, Drs. Vavalle and Ohman note, this experience speaks to the need for postmarket surveillance systems to gather long-term data not only for safety but for efficacy.

Weighing When IABPs Are Needed

William W. O’Neill, MD, of the Leonard M. Miller School of Medicine (Miami, FL), who served as principal investigator for PROTECT-II, told TCTMD in a telephone interview that he suspects a causative link between better hemodynamic support and lower long-term mortality. In both PROTECT-II and BCIS-1, the “curves start to splay” at 3 months, he said. “There’s a consistency between the 2 trials that’s really important. . . . There’s a signal there.”

Controversy currently exists regarding the use of IABP therapy during high-risk PCI in clinical practice, Dr. O’Neill noted. “Some doctors say, ‘I don’t need any hemodynamic support at all, and the patients will do fine.” This may be true in some cases, but it can be difficult to identify which patients need more support, he stressed. “If there’s a lot of complex disease that needs to be treated—extensive stenting, bifurcation stenting, or just a very elaborate procedure—then I think you absolutely need hemodynamic support.”

In a telephone interview with TCTMD, Sorin J. Brener, MD, of Weill Cornell Medical College (New York, NY), expressed less enthusiasm for IABP use. “It’s pretty rare right now. Certainly, if I think the patient is so sick that he needs ventricular support, I would rather use an Impella than a balloon pump,” he said, noting that despite being high risk, patients undergoing elective PCI need less hemodynamic support than acute MI patients. “There, it’s a different story.”

Dr. Brener noted that potential downsides to IABP use are patient discomfort and the risk of bleeding or vascular complications.

BCIS-1 “should prompt all of us to try to think of both a mechanism as well as how the concept could be proven,” Dr. Brener concluded, suggesting that experimental animal models might be helpful. At this point, he added, “it’s really hard to come up with [a convincing explanation].”

According to Dr. O’Neill, BCIS-1 and PROTECT-II are likely to turn the tide toward more hemodynamic support “once the data get out and get promulgated. . . . There weren’t any true randomized data before.”

 

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Sources:
1. Perera D, Stables R, Clayton T, et al. Long-term mortality data from the Balloon pump-assisted Coronary Intervention Study (BCIS-1): A randomized controlled trial of elective balloon counterpulsation during high-risk PCI.  Circulation. 2012;Epub ahead of print.

2. Vavalle JP, Ohman EM. Left ventricular support systems for high-risk PCI: How can we improve outcomes for rare procedures? Circulation. 2012;Epub ahead of print.

3. Perera D, Stables R, Thomas M, et al. Elective intra-aortic balloon counterpulsation during high-risk percutaneous coronary intervention: A randomized controlled trial. JAMA. 2010;304:867-874.

 

 

Related Stories:

• BCIS-1: Long-Term Follow-up Shows Lower Mortality with Elective IABP Therapy
• No Benefit Seen with Elective IABP in High-Risk PCI Patients
• PROTECT II Published: Study of Percutaneous LVAD vs. IABP Sends Mixed Signals