Impella: A Revolutionary Device Being Questioned

Observational studies (with their subsequent limitations) show a possible increase in adverse events and costs with the use of the Impella device.

Two large observational studies stirred doubts regarding the good performance of new circulatory support devices in real-world daily clinical practice.

There were more adverse events, including in-hospital death and major bleeding, and more costs with left ventricular assist device Impella vs. classic intra-aortic balloon counterpulsation.

These data must obviously be analyzed with caution, given the great methodological limitations of the aforementioned works, but they do encourage us to think harder about when to use this device and in whom.

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One of these studies, presented at the American Heart Association (AHA) 2019 Congress and simultaneously published in Circulation, enrolled an astonishing number of subjects: 48,306 patients who underwent angioplasty with a circulatory support device in 400 sites. Among them, 9.9% of the circulatory support devices were Impella; however, that number rose over time and reached 31.9% in 2016. Impella was less used in more critical patients (those who received mechanical ventilation, had cardiac arrest, or had a diagnosis of cardiogenic shock) and it was more used in patients relatively less sick.

There was great dispersion regarding device use and complications across sites. For example, the rate of bleeding in some hospitals more than doubled the same rate in others, while the rates of death, acute kidney injury, and stroke varied in up to 50% among sites.

The higher financial cost of Impella, compared with intra-aortic balloon counterpulsation, was consistent throughout the whole study.

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After propensity score matching to allow for population comparison, Impella was associated with higher rates of mortality (odds ratio [OR]: 1.24; 95% confidence interval [CI]: 1.13-1.36), bleeding (OR: 1.10; 95% CI: 1.00-1.21), and stroke (OR: 1.34; 95% CI: 1.18-1.53), and a non-significant trend towards higher rates of acute kidney injury (OR: 1.08; 95% CI: 1.00-1.17).

Such comparison with propensity score matching can also be subject to objections from a methodological point of view, given the great dispersion of variables in different sites using the device.

Original title: The evolving landscape of Impella use in the United States among patients undergoing percutaneous coronary intervention with mechanical circulatory support.

Reference: Amin AP et al. Circulation. 2019; Epub ahead of print.

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