Steep Rise in PVAD Support for Protected PCI: Medicare Data

By 2018, percutaneous left ventricular assist devices (PVADs) overtook intra-aortic balloon pump (IABP) therapy as the predominant form of mechanical circulatory support (MCS) in high-risk percutaneous coronary interventions, according to an analysis of Medicare data spanning 7 years.

The annual number of PVAD-supported PCIs more than quadrupled between 2013 and 2019, researchers found, a pattern in line with earlier studies showing similar growth in the cardiogenic shock space.

Yet “there is a large variation in healthcare markets across the United States with regards to their utilization of PVADs for supported PCI,” senior study author Saket Girotra, MD, SM (University of Texas Southwestern Medical Center, Dallas), told TCTMD. The extent of this variation—wherein PVADs were twice as likely to be used in some areas versus others, irrespective of patient, hospital, and market characteristics—“suggests that there is a lot of uncertainty about what the best option is in terms of device choice,” he said.

The analysis, led by Thorarinn A. Bjarnason, MD, PhD (University of Iowa Carver College of Medicine, Iowa City), and published recently in Circulation: Cardiovascular Interventions, relies on administrative data. As such, it’s unable to distinguish how many of the PVADs were Impella (Abiomed) versus TandemHeart (LivaNova), which share the same ICD procedure code. However, the researchers conjecture that most cases involved Impella—its manufacturer has reported that more than 200,000 patients have received the device thus far.

Bjarnason and colleagues also found that regions with the highest PVAD use saw no difference in 30-day mortality, but did have higher average hospitalization costs.

Impella “is an exciting device,” Girotra noted. “It provides more hemodynamic support compared to an intra-aortic balloon pump. We know that. But we still do not have convincing randomized controlled trial data that demonstrate that this is truly effective in reducing mortality and other hard clinical endpoints.”

Mixed Reactions

Behnam N. Tehrani, MD (Inova Heart and Vascular Institute, Falls Church, VA), commenting on the observational analysis, said that it’s “interesting” but also serves as yet another reminder of the need for randomized controlled trials. With these, he said, “we can develop some standardized practices around device insertion and management.”

Daniel Burkhoff, MD, PhD (Cardiovascular Research foundation, New York, NY), on the other hand, found little of interest in the data, noting, “This is yet another study using an administrative database.” What most readers of the paper are likely to focus on are the data related to mortality and cost, not the patterns in PVAD usage, he predicted.

“With every conclusion, there’s an alternate interpretation,” Burkhoff said, questioning why journals continue to publish observational analyses that are “wholly inadequate. . . . All they do is confuse the field. They have not influenced practice.”

Indeed, as this paper points out, PVAD use has continued to grow. This has occurred despite various database-derived analyses that “continue to show Impella is associated with more complications and worse outcomes,” Burkhoff observed. There is no likely reason for this association, “as far as we can tell,” other than that “Impella is being used in sicker patients than balloon pump,” he said. “The databases have no way of dissecting that out.”

Specific to their study, which is largely about protected PCI but also includes some patients experiencing cardiogenic shock, Girotra acknowledged “it’s hard for us to figure out what may be driving [the regional variation].” The Centers for Medicare & Medicaid Services data provide a way to assess care delivery patterns across the country in a subset of the US population, he added. “But they have their limitations. We do not have granular information regarding clinical variables that we care about—for example, the complexity of their coronary artery disease or the severity of their shock.”

A Shift Seen in 2018

Between 2013 and 2019, there were 79,176 Medicare beneficiaries who underwent PCI with support from IABP (60%) or PVAD (40%). At the start of the period, in 2013, just 17% of the PCIs involved PVADs, whereas these devices predominated as of 2018, rising to 57% in 2019. Moreover, the total number of PCI procedures involving IABP dropped from 7,092 in 2013 to 6,225 in 2019. For PVADs, the opposite was seen: rising from 1,492 PCIs in 2013 to 8,231 in 2019 (both P for trend < 0.001).

In terms of patient characteristics, 84.6% of the PVAD group were white and 64.2% were male. Their mean age was 76.1 years. Around two-thirds were admitted with acute MI and 57.1% had cardiogenic shock.

Patients treated in regions where there was more PVAD use were less apt to be white and more likely to have dual Medicare/Medicaid eligibility. Somewhat surprisingly, the sickest patients—those with acute MI, cardiogenic shock, and emergent status—were 45% to 50% less likely to receive PVAD versus IABP support.

Mean hospital costs were higher among the PVAD-supported patients than among those receiving IABP therapy ($53,691 vs $25,498; P < 0.001). Hospitals seeing greater PVAD use were more frequently for-profit centers and more often located in the southern United States.

The researchers used the Dartmouth Atlas Project to map each hospital into a corresponding referral region. Across healthcare regions, there was a wide range of PVAD use in PCI: from as low as zero to as high as 85%. Adjusting for patient characteristics, hospital, and market variables did nothing to reduce the variation (median OR 2.07; 95% CI 1.93-2.20) from one randomly selected hospital referral region to the next. Areas with the highest quartile of PVAD use tended to be larger, have more hospitals, and be highly competitive. Additionally, at the regional level, greater PVAD use was not linked to 30-day risk-adjusted mortality—which ranged from 31.5% to 31.0% in the lowest versus highest quartiles of use—but was associated with higher cost.

Why the Variation?

Burkhoff’s view is that operators’ firsthand experience with Impella is what’s driving the uptake: the study itself offers no clues as to what’s responsible for the variation. “People who use Impella can see the hemodynamic benefits of Impella compared to balloon pump, [which] we know doesn’t provide any meaningful clinical support in a majority of patients,” he noted. Moreover, IABP did no better than optimal medical therapy alone in the 2013 IABP-SHOCK II trial, Burkhoff added.

“Hemodynamics,” Burkhoff acknowledged, “are not always associated with clinical outcomes.” But the fact that earlier hemodynamic support appears to provide better survival is an indicator that this metric matters, he said.

In an editorial, Zaid I. Almarzooq, MBBCh, MPH, and Robert W. Yeh, MD, MSc, MBA (Beth Israel Deaconess Medical Center, Boston, MA), point to other factors that may be driving the uneven uptake of PVADs, such as “regional differences in training, familiarity, beliefs, and device availability,” across the United States.

“Given the debate over the quality of evidence supporting PVADs and the lack of a Class I indication supporting their use, it may not be completely surprising to see such wide variation in the use of these devices between markets,” they write.

They caution, though, that the association between market-level PVAD use and outcomes does not indicate causality. Potential confounders include not just patient factors but also hospital and region-level characteristics “such as institutional capabilities, regional transfer patterns for high-acuity patients, and community-level disadvantage,” Almarzooq and Yeh say. Nor do the MCS-supported patients represent the entirety of the PCI population, which makes it difficult to ascertain whether there’s a “risk-treatment paradox,” wherein more-severe cases were less apt to receive PVADs.

Forthcoming RCT data “will likely provide greater clarity regarding the right place for PVADs in our care of patients, clarity which has eluded observational comparisons and epidemiological descriptions. Until then, however, it is likely that passionate debate both for and against the use of PVADs to support patients undergoing complex PCI procedures will continue,” they conclude.

What Are Clinicians to Do?

In 2012, the randomized PROTECT II trial found no difference in 30-day major adverse events, its primary endpoint, between patients randomized to Impella or IABP, though a per-protocol comparison at 90 days found fewer events with Impella. Based on PROTECT II and its predecessor PROTECT I, Impella received US Food and Drug Administration premarket approval in 2015 for elective and urgent high-risk procedures. More recently, in 2020, data from the single-arm PROTECT III postapproval study suggested that growing familiarity with the device and better patient selection are leading to better outcomes in high-risk PCI.

“We know that there are some randomized controlled trials that are currently ongoing. I, along with others in the community, are eagerly awaiting those trials,” Girotra said, citing PROTECT IV, which is recruiting high-risk patients with complex CAD and reduced LV function. Also on the horizon are DanGer, an ongoing RCT in patients with acute MI complicated by cardiogenic shock, as well as RECOVER IV, which recently received FDA approval to begin.

Tehrani said that, for now, treatment needs to be tailored to each situation. “Until we have randomized clinical trials to inform overall management, as a whole, the care for patients undergoing high-risk PCI and undergoing cardiogenic shock comes down to best clinical judgment, expertise at the individual hospital and by the operator doing the procedure, and best practices for management of the device afterwards,” he advised.

In his own practice, he “has used Impella quite frequently,” Tehrani added. “I think it’s a device that we should very much respect. It’s a very important therapy, but we just don’t know which patients it should be used for.”

Trials will hopefully provide some answers in the coming years, said Burkhoff. He cautioned, though, that if the experience with IABP-SHOCK II is any guide, even randomized data may not settle debates. “There are people who firmly believe in protected PCI with Impella, and there are those that don’t. I think it’s a field where personal bias and experience are going to continue to prevail for a very long time,” he said.

In the meantime, said Burkhoff, cardiologists need to use their judgement. “Clinicians need to treat patients. And they need to weigh the available evidence as they see it to help guide their clinical practice [along with] their experience.”