In-hospital Mortality Higher When IABPs Deployed During PCI

There are more data linking intra-aortic balloon pumps (IABPs) and worse outcomes for PCI patients, this time from a Japanese study that considered patients being treated for both urgent and elective procedures. Use of the devices in the study was associated with an increase in in-hospital mortality.

The findings “suggest that it is time to reconsider the appropriate use of IABP therapy, a potentially life-saving but extremely costly and high-risk intervention for patients,” Shun Kohsaka, MD, PhD, of Keio University (Tokyo, Japan), and colleagues write in a research letter in JAMA Internal Medicine.

The investigators examined data from a multicenter PCI registry (Japan Cardiovascular Database-Keio Interhospital Cardiovascular Studies) on 13,253 patients treated between September 2, 2008, and May 19, 2014, for both acute and nonacute indications. Roughly equal numbers of procedures were performed for STEMI (23.9%) and NSTEMI or unstable angina (24.2%).

An IABP was inserted in 6.7% of patients. Use of the device was associated with a higher rate of in-hospital mortality before adjustment (15.1% vs 0.9%), and the link was maintained after accounting for baseline differences (adjusted OR 3.87; 95% CI 2.71-5.52).

That relationship was consistent across patient subgroups believed to have potential indications for IABPs, including those with cardiogenic shock, STEMI, a lesion in the left main trunk, NYHA class III or higher symptoms, unstable angina, triple-vessel disease, and NSTEMI. The ORs grew with weaker indications for IABP use, the authors report.

Though limited by the study’s observational design, the potential for confounding by unmeasured factors, and the lack of information on reasons for IABP insertion, the results support those of a recent meta-analysis in which IABP use was tied to increased mortality in certain subgroups of acute MI patients, Kohsaka and colleagues say.

Mechanical Circulatory Support Use Increasing

In an invited commentary, Prakash Deedwania, MD, and Tushar Acharya, MD, of the University of California San Francisco, point out that use of mechanical circulatory support (MCS) devices has been growing in recent years, driven largely by newer percutaneous ventricular assist devices (PVADs) such as Impella (Abiomed) and TandemHeart (CardiacAssist). Although studies indicate that IABP use is rising at a much slower pace—or even declining—IABPs are still used much more frequently than PVADs.

“However, increased implantation of IABPs or PVADs is not supported by any evidence of clinical benefit or by professional guidelines,” Deedwania and Acharya note. In the IABP-SHOCK II trial, for example, IABP use failed to improve survival in patients with MI-related heart failure or shock. And in the CRISP AMI trial, IABP therapy during primary PCI did not reduce infarct size or improve clinical outcomes in STEMI patients without shock.

Initial studies of PVADs have been similarly lackluster. In a meta-analysis, PVADs did not reduce 30-day mortality in patients with cardiogenic shock after acute MI compared with IABPs and were associated with an increased bleeding risk. In the PROTECT II trial, Impella 2.5 did not improve 30-day outcomes vs IABP therapy in high-risk patients undergoing PCI.

Clinicians may be reluctant to stop using MCS devices despite the lack of supporting evidence for several reasons, Deedwania and Acharya say, including a belief that they might be useful as salvage therapy in patients with cardiogenic shock complicating acute MI, who have a mortality rate as high as 50%, possible “misaligned financial incentives,” and the presence of “established routines or treatment protocols, with commission bias tending toward action rather than inaction.”

Based on the accumulated studies, “the use of these invasive and expensive mechanical circulatory support devices should be critically appraised and limited because of significant complication rates associated with their use and a lack of evidence demonstrating any benefit,” they conclude. “In the use of IABPs and PVADs, it seems appropriate to conclude that perhaps less is more.”

Sources: 
1. Inohara T, Miyata H, Ueda I, et al. Use of intra-aortic balloon pump in a Japanese multicenter percutaneous coronary intervention registry. JAMA Intern Med. 2015;Epub ahead of print.
2. Deedwania P, Acharya T. Is increased use of mechanical circulatory support devices justified? A cause for concern [invited commentary]. JAMA Intern Med. 2015;Epub ahead of print. 

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