BCIS-1: Long-Term Follow-up Shows Lower Mortality with Elective IABP Therapy
CHICAGO, IL—Contrary to shorter-term results, follow-up beyond 4 years shows that elective intra-aortic balloon pump (IABP) therapy in high-risk patients receiving percutaneous coronary intervention (PCI) reduces mortality by roughly a third, according to results presented March 24, 2012, at the annual American College of Cardiology/i2 Scientific Session.
For the Balloon pump-assisted Coronary Intervention Study (BCIS-1), researchers assessed the efficacy and safety of elective IABP use in 301 patients with multivessel coronary disease and severe left ventricular dysfunction (LVEF ≤ 30%) undergoing PCI. Patients were randomized to receive IABP support (n = 151) or no planned IABP (n = 150) at 17 tertiary referral cardiac centers in the United Kingdom between December 2005 and January 2009.
As reported 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).
Longer Follow-up, Different Story
In long-term results presented by Divaka Perera, MRCP, MD, of St. Thomas’ Hospital, King’s College London (London, United Kingdom), a 33% mortality rate was demonstrated in BCIS-1 patients over a median follow-up of slightly over 4 years (51 months). In addition, IABP use led to a 34% reduction in mortality (HR 0.66; 95% CI 0.44-0.98; P = 0.03), with 42 deaths in the IABP arm (27.8%) and 58 in the no-IABP arm (38.7%). The mortality rate per 100 person-years was 7.89 with IABP and 12.08 without.
Dr. Perera noted that the overall results suggest a treatment effect that starts to become apparent around 6 months, when the previous follow-up ended. But the exact mechanism for why IABP should provide a mortality benefit remains elusive.
For instance, peri-procedural ischemia and infarct size were not reduced with IABP therapy, nor were there any differences in revascularization characteristics between the IABP and no-IABP groups.
“The mode of death and the putative mechanism of benefit of counterpulsation are unclear at present,” Dr. Perera said, concluding nevertheless that “this seems to be a real effect. Elective IABP use during PCI was associated with an observed 34% reduction in long-term all-cause mortality.”
Cause of Death Missing
However, audience member Sorin J. Brener, MD, of Weill Cornell Medical College (New York, NY) remained doubtful. “I think when things are too good to be true, they usually are,” he said.
Panel co-chair Patrick W. Serruys, MD, PhD, of Erasmus Medical Center (Rotterdam, The Netherlands) called the results, “fascinating,” and the report, “a positive trial with no mechanistic interpretation.”
He added that details concerning the mode of death for patients in the trial would certainly help explain the results. “It’s obvious that if you had the details, the narratives of the deaths, it would be encouraging and facilitate the interpretation,” he said. “Having the narrative could help you tell the difference between cancer or sudden death. It would help clarify [the mortality reduction].”
Unfortunately, all-cause mortality for BCIS-1 was collected by central database. “I agree entirely that we need to know the cause of death,” Dr. Perera said. “We can’t really dissect out how this putative benefit might have happened.”
Perera D. Balloon-pump assisted Coronary Intervention Study (BCIS-1): Long-term mortality data. Presented at: American College of Cardiology Scientific Session; March 24, 2012; Chicago, IL.
- BCIS-1 was supported by unrestricted educational grants from Datascope (now Maquet) and Cordis. Abciximab was provided by Lilly.
- BCIS-1 extended follow-up was supported by an unrestricted educational grant from Maquet Cardiovascular.
- Dr. Perera reports no relevant conflicts of interest.