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IABP Associated With a Long-Term Reduction in Mortality: BCIS-1

March 27, 2012 (Chicago, Illinois) — Long-term data from the Balloon-Pump Assisted Coronary Intervention Study (BCIS)-1 suggests that the use of an intra-aortic balloon pump (IABP) in patients with low ejection fraction undergoing high-risk angioplasty procedures is associated with a lower long-term risk of mortality. Researchers report that the elective use of IABP during PCI was associated with a 34% reduction in the risk of death after a median follow-up of 51 months.
The mortality benefit contrasts with the overall negative results of BCIS-1, a study that showed there was no difference in the risk of major adverse cardiac and cerebrovascular events (MACCE) at the time of hospital discharge among patients treated with IABP when compared with those who did receive counterpulsation.
The results of the newest analysis were presented this week at the American College of Cardiology (ACC) 2012 Scientific Sessions by Dr Divaka Perera (St Thomas' Hospital, London, UK). To heartwire, Perera said investigators do not know why the patients died, and the researchers caution against overinterpreting the data.
Dr Divaka Perera
"We saw the curves diverging, but the numbers were just too small," said Perera. "We also didn't know how the results would play out. At the time, back in 2009, there were few published data on how ischemic-cardiomyopathy patients would do, especially since the STICH trial wasn't published yet. When you look at the two trials, the BCIS-1 trial had an even sicker population than STICH. The overall mortality was much higher than we actually thought it would be."
After slightly more than four years, 33% of the 301 enrolled patients in BCIS-1 died.
BCIS-1 Presented at TCT 2009
In the BCIS-1 trial, which was first presented at TCT 2009 by Dr Simon Redwood (King's College, London, UK), the researchers randomized patients to either elective IABP use or "no planned" IABP use, with bailout IABP permitted. All patients had to have an ejection fraction of <30% and extensive myocardium at risk, which was defined either as a coronary occlusion of a vessel supplying at least 40% of the myocardium or by a myocardial jeopardy score >8.
Using data from the Office of National Statistics in England and the General Register's Office in Scotland, Perera and colleagues collected mortality data for every patient participating in BCIS-1. During a median follow-up of 51 months, there were 100 deaths, with 42 patients in the IABP arm and 58 patients in the no-planned-IABP arm dying. This resulted in a statistically significant 34% reduction in the risk of death with IABP (hazard ratio 0.66; 95% CI 0.44-0.98).
During the presentation, Perera said they do not yet understand why counterpulsation resulted in a long-term mortality benefit. There was no improvement in the predefined MACCE rate at hospital discharge and there was no reduction in infarct size observed in other studies, namely CRISP-AMI. In addition, the BCIS-1 study did not suggest there were any differences in the revascularization characteristics in the two groups of patients, suggesting that more complete revascularization was not responsible for the improvement in the IABP arm.
"We want to be careful," said Perera. "All-cause mortality wasn't a prespecified end point, and we don't yet have a mechanism. These are two main limitations of the analysis. I think we need to do another trial. . . . We don't know why they died, but looking at other data and experiences, we know that these patients die of arrhythmias and pump failure, but mainly arrhythmias. If and when we do the follow-up study, we want to carefully look at arrhythmias to try to pin down exactly what happens to periprocedural infarcts with and without a balloon pump."

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