Mechanical Circulatory Support Growing More Common During PCI

Mechanical circulatory support (MCS) devices are increasingly being used for PCI in the United States despite mixed results from trials and registries, an observational study shows. In addition, outcomes—particularly in-hospital mortality—are similar for percutaneous ventricular assist devices (PVADs) and intra-aortic balloon pumps (IABPs).

Although IABPs continue to be deployed the most, PVAD use is growing at a faster rate, according to results published online October, 15, 2015, ahead of print in the American Journal of Cardiology.

“Since the number of high-risk PCI procedures requiring the use of MCS devices is likely to rise, further evidence from randomized controlled studies is needed to guide selection of patients undergoing PCI, who might benefit from one MCS device over another, given the incremental cost and risk of complications associated with the use of PVADs over IABP,” write Rohan Khera, MD, of the University of Iowa Hospitals & Clinics in Iowa City, and colleagues.

They examined data from the National Inpatient Sample on 1,041 patients receiving PVADs, including Impella (Abiomed) and TandemHeart (CardiacAssist), and 25,636 receiving IABPs on the same day as PCI between 2004 and 2012. That translates into 5,031 receiving PVADs and 122,333 receiving IABPs across the United States during the study period.

MCS was used in 2.1% of all procedures during this period, increasing from 1.3% in 2004 to 3.4% in 2012 (P < .0001 for trend). The rise was seen across patient subgroups and for both PVADs (from < 1 to 38 per 10,000 PCIs) and IABPs (from 132 to 299 per 10,000 PCIs; P < .0001 for both).

Similar Outcomes With PVADs, IABPs

Patients who received IABPs were more likely to have high-acuity conditions, including acute MI, cardiogenic shock, and cardiac arrest, compared with those who received PVADs, and they were less likely to have chronic comorbidities and to be treated electively. Those differences translated into a lower unadjusted in-hospital mortality rate among those treated with PVADs (12.8% vs 20.6%; P < .0001). After accounting for those differences in patient characteristics with propensity matching, however, the disparity did not reach statistical significance either in the overall cohort or across patient subgroups.

Limited Evidence of Benefit

There are multiple likely explanations for the rise in MCS use during high-risk PCI, the authors say, including the expansion of PCI to patients previously deemed too high risk, a shift stemming from advances in techniques and greater operator experience. Also, they say, there is an assumption that maintaining coronary blood flow, especially during balloon inflation and stent deployment, will be beneficial in high-risk patients, who have twice the risk of mortality compared with other patients.

“However, randomized trials have not shown a reduction in PCI-related mortality with the use of either [PVADs or IABPs] in PCI and ACC/AHA guidelines recommend their use in high-risk PCI as a Class IIb indication,” Dr. Khera and colleagues write. “Experts have acknowledged the utility of these devices but have called for studies to guide appropriate use.”

Prior randomized trials of MCS devices have yielded mixed results. BCIS-1 showed that elective use of IABPs did not reduce MACCE at hospital discharge or mortality at 6 months, although there was a reduction in mortality through a median follow-up of 51 months.

The IABP-SHOCK II trial, which included patients with acute MI and cardiogenic shock, failed to show a reduction in all-cause mortality or MACCE at 12 months with IABP use. Furthermore, a recent meta-analysis found no effect on 30-day mortality with IABP use in acute MI patients with or without cardiogenic shock.

There is similarly weak evidence to support the use of PVADs. In the PROTECT II trial, for example, Impella did not improve 30-day outcomes after high-risk PCI vs IABPs, although a per-protocol analysis suggested an advantage for the PVAD at 90 days.

“Therefore, there is significant subjectivity in the selection of patients where MCS devices are used during PCI and [that] is likely determined by operator preference or institutional policies,” the authors write.

They add that a dedicated study should focus on whether overuse of MCS in low-risk patients might explain some of the recent increase in deployment of PVADs and IABPs.

Source:
Khera R, Cram P, Vaughan-Sarrazin M, et al. Use of mechanical circulatory support in percutaneous coronary intervention in the United States. Am J Cardiol. 2015;Epub ahead of print.