Evaluating Clinical Data and Economic Impact of Cardiac Assist Devices in High-Risk Patients

Intra-aortic balloon pumps (IABP) aim to provide transient support of left ventricular function in cases of failure during an ischemic or non-ischemic insult. The most frequent indications for use of IABP are hemodynamic support during or after cardiac catheterization, cardiogenic shock, weaning from cardiopulmonary bypass, preoperative use in high-risk patients, and refractory unstable angina.¹

Percutaneous left ventricle assist devices are a new option for partial or total circulatory support, and several studies have compared their safety and efficacy with IABP. Without a distinct advantage in mortality in either device, is it time to evaluate the impact of cost on the healthcare system?

Device overview

The first commercial IABP (Maquet) was introduced in 1971, and has set the standard of care for patients. A small balloon catheter inserted into the aorta to decrease myocardial oxygen demand and increase myocardial oxygen supply has increased patient survival rate. Over the last four decades, the system behind the balloon has undergone significant technological advances, in addition to a decrease in size from a 12 French catheter to the current 7.5 French versions. Evolutions in technology have allowed faster times to therapy, faster signal acquisition, and faster adaptation to rate and rhythm changes. Advances in computerized equipment in general have also allowed the IABP machine to get smaller and lighter, allowing for the transport of critically ill IABP patients to other facilities for definitive treatment. The most recent IABP, the Cardiosave (Maquet), employs fiber-optic speeds, 50cc balloons, and very intuitive and intelligent counter-pulsation therapy.

The technological evolution of the IABP has been accompanied by such extensive usage that any physician in a cardiac catheterization laboratory is sufficiently familiar with the IABP such that it is considered very easy to use, and all can troubleshoot if something goes wrong. IABP has been proven to provide initial hemodynamic stabilization²  by actively deflating in systole, inflating in diastole, increasing coronary flow, and increasing circulation. 

Percutaneous LVADs (often called pVADS), an emerging option for partial or total circulatory support, differentiate themselves from IABPs in their ability to provide active circulatory support and actually unload the left ventricle. This minimally invasive option is inserted through a 13 French sheath in the common femoral artery and inserted through the aortic valve into the left ventricle. The Impella 2.5 device (Abiomed) removes the blood from the left ventricle and pumps it into the ascending aorta at a maximum flow rate of 2.5 L/min without requiring a transseptal puncture, which is required for insertion of the TandemHeart device. The pVAD offers more challenges with insertion, often requiring navigation across a stenotic or sclerotic aortic valve. Furthermore, the 13 French sheath often precludes insertion in patients that are elderly, very thin, or with peripheral arterial disease that makes it impossible to navigate the femoral artery. 

Trial outcomes

A number of studies have been performed to compare the efficacy of IABP versus the Impella 2.5 with clinical and hemodynamic endpoints in a variety of clinical settings. An initial trial³ of 26 patients with cardiogenic shock due to acute myocardial infarction randomized patients to either the IABP or the Impella 2.5 with implantation after percutaneous coronary intervention. In this group of patients, the pVAD device resulted in a greater change in 30-minute cardiac index compared with IABP; however, at all measured time points the cardiac index was similar between the groups. The investigators found the mean time required to implant an IABP was 14 minutes versus 22 minutes for the Impella device.³ 

Investigators undertook a large-scale trial, PROTECT II, to attempt to tease out a difference in survival rates between the devices.⁴ In 452 patients undergoing high-risk percutaneous coronary intervention randomly assigned to either IABP or the Impella 2.5 device, the overarching equality of the treatment options was confirmed: the 30-day incidence of major adverse events was not statistically different. The trial was terminated when the interim analysis showed futility determination regarding the primary endpoint, which was a composite of major adverse cardiovascular events including death, myocardial infarction, cerebrovascular accidents, and repeat revascularization.

Detailed analysis of the PROTECT II trial did show some interesting evaluations. Operators in the trial tended to combine use of the percutaneous pVAD with aggressive rotational atherectomy, which is known to trigger the release of periprocedural creatine kinase, a myocardial enzyme linked to MI and higher mortality risk. In the sub-group of patients treated without atherectomy, the pVAD did show significantly fewer adverse events (29.5%) as compared to IABP (42.4%). In addition, patients with severe depression of left ventricle function may not receive sufficient hemodynamic support from IABP to reverse cardiogenic shock, and could benefit from the active circulatory support of a pVAD.⁵

A recent meta-analysis of controlled trials reported that although a pVAD may provide superior hemodynamic support, use of pVADs does not correspond to improved early survival rates, and trial results do not yet support pLVAD as a first-choice approach in the mechanical management of cardiogenic shock.⁶ In patients that need substantial hemodynamic support, operators may turn to the Impella 5.0, Impella CP, or the TandemHeart device. The Impella 5.0 requires a surgical cut down and further trials are needed to demonstrate clinical superiority over the IABP. 

Considering cost

Human life is considered to have the ultimate value and the best treatment should be provided no matter the cost. However, given the lack of a distinct superiority of one device over another, one should ask, “should procedural cost be considered?” At the current time, under the Medicare payment system, a pVAD is a short-term, minimally invasive device, with a reimbursement rate higher than the IABP, reflecting the more expensive cost of the item. Private payer levels vary across the country depending on each carrier’s determination as to the status and covered indications of the pVAD. The true comparison starts with the acute clinical situation being addressed with an IABP that costs $800-$1000 or a percutaneous pVAD that costs between $21,000-$23,000. Considering that these costs may be paid by Medicare, which is taxpayer money, or insurance companies, which distribute the expense over the payer base, the result is a significant burden to society if the device is not truly necessary. 

Similar cost concerns hold true for patients without insurance or small private payers that do not cover the pVAD device, in which case the patient is responsible for the full price of the pVAD, which may approach $100,000. In today’s health care environment, cost effectiveness is of critical importance. Meaningful use and other quality metrics have become part of the physician’s lexicon and no health care provider is immune from the financial aspects of clinical practice. Studies investigating the cost effectiveness and quality of life years (QALYs) are critically important in determining not only the best care for every individual patient, but to our society. Currently, cost-effectiveness trials and analysis comparing the support devices are ongoing and necessary to our understanding and choice of the most appropriate device.

The ultimate determination

When a patient crashes due to acute cardiogenic shock, I and most other interventionalists would not think twice about immediately using an IABP. It can be inserted quickly and hemodynamic stability can be achieved in the shortest amount of time possible. Not only are physicians comfortable with the IABP, but so are nurses and technologists. Furthermore, the IABP can be inserted bedside in an expeditious manner. Use of an IABP does not preclude choosing additional support later. There are other unique situations in which an IABP would confer an advantage over pVAD. Recent long-term mortality data from the balloon pump-assisted coronary intervention study (BCIS-1)⁷ reports a 34% reduction in mortality when IABP is used in a high-risk percutaneous coronary intervention (PCI) population. This is important data to consider in the context of the ISAR-SHOCK and PROTECT II trials. Neither of these trials showed a net clinical advantage to pVAD, while they did show a significant increase in risk. There was a higher need for transfusions and an increased risk of vascular complications. In a high-risk, elective PCI situation, the smaller-profile IABP allows more immediate hemodynamic support. These new studies reinforce previous data from Seyfarth and colleagues that in patients with cardiogenic shock with acute MI, there is no clear benefit to the pLVAD, but there is an increased risk of hemolysis compared to IABP.³ 

In regards to cost effectiveness, Talley et al have reported that the use of prophylactic IABP with hemodynamically significant myocardial infarction is associated with improved clinical outcomes without a significant increase in hospital cost.⁸

Another particular niche for IABP is for the end stage heart failure patient who is awaiting transplant. Chronic support through a device in the femoral artery can limit mobility, resulting in patient reconditioning and difficulty in rehabilitation post-surgery. The IABP can be placed via the subclavian artery in a minimally invasive approach, which allows for hemodynamic support and ambulation for the patient awaiting transplant.⁹ And finally, the use of IABP in patients who have return of spontaneous circulation (ROSC) after out-of-hospital cardiac arrest occurs in almost 90% of trial patients.

Final analysis

In summary, while some hemodynamic parameters may improve with the pVAD compared to the IABP, no trial has demonstrated a significant clinical advantage to the use of pVAD compared to IABP. In addition, the larger sheath size needed to insert the pVAD can cause increased vascular complications and higher transfusion needs. And pVAD associated hemolysis remains difficult to manage. Given the currently available data, in an acutely ill patient, the fastest, safest, and most effective hemodynamic support option remains the IABP, which is both medically proven and cost-conscious. 

Disclosures: Dr. Shah reports the following:

Grants: past partial funding NIH NHLBI R01HL076671, Medtronic

Consultant: Velomedix, Physio-Control, Maquet, Medtronic

Speakers Bureau: Medtronic, AstraZeneca, Novartis

Site Primary Investigator: St. Jude Medical

Atman P. Shah can be reached at ashah@bsd.uchicago.edu.

References 

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