The Comparative Use of Ventricular Assist Devices: Differences between Europe and the United States

In the field of mechanical circulatory support and transplantation, there are several differences between Europe and the United States. The population of Europe is 731,000,000 and the population of the U.S. (2008 U.S. Census Bureau estimate) is 305,529,237. Currently, the estimated total number of long-term devices implanted in the U.S. per year is over 1,700, compared with over 430 per year in Europe. Europe's multiple countries are very diverse in their levels of wealth and in their philosophies towards healthcare. An estimate of the population of European and nearby countries is shown in Table I; those that currently play an important role in the ventricular assist device (VAD) field appear in bold type. TABLE I. The Populations of Major European (and Nearby) Countries Of course, the funding and regulation of device implantations in each country significantly affects that country's role in the field. There are many European countries in which long-term VADs are funded only as a bridge to transplantation, often with only limited numbers funded; and in other countries, funding for destination therapy is present but very limited. Many countries have no formal VAD funding at all. The European numbers are currently dominated by Germany, which does not limit funding by indication for either bridge-to-transplantation or destination therapy and is able to implant devices, with good reimbursement, in all patients who need one. Of the 3 large German centers (Berlin, Bad Oeynhausen, and Hannover), each of the first 2 has implanted devices in more than 1,000 patients. In France, the government has recently doubled the number of devices funded. Bridge to Transplantation Only The United Kingdom limits funding to bridge to transplantation, which changes not just the number of devices implanted and patients treated, but the whole approach to the patient. Although the population of the U.K. stands at almost 62 million, the heart transplantation numbers (as in other countries) have decreased significantly—to fewer than 100 adult transplants per year, in the whole of the U.K. This is totally inadequate to treat the number of patients with heart failure requiring transplantation. When only a bridge-to-transplantation program is funded, every patient has to be either a transplant candidate or a potential transplant candidate (that is, after a period of VAD support). We know from Interagency Registry for Mechanically Assisted Circulatory Support data that eligibility for heart transplantation is difficult to predict and that many destination-therapy patients later become candidates for transplantation. Hence, the bridge-to-transplantation-only program leads to palliative care for some patients who would have become good transplant candidates following a period of VAD support. Moreover, this approach limits the number of devices that can be justified: when patients receive implants only as a bridge to transplantation, the number of implants is limited by the number of transplants, which continues to fall. This approach is counterproductive if the goal of VAD therapy is to treat more patients who have advanced heart failure. In addition, under the constraints of bridge-to-transplantation-only funding, many cardiologists delay referrals for VAD implantations in the hope of directly obtaining a heart transplant for the patient, thereby avoiding a 2nd operation; in the meanwhile, the patient often deteriorates (on inotropic support), waiting for heart transplantation. By the time such patients receive their VADs, they often have developed right-heart failure (leaving patients in left-heart failure often leads to right-heart failure), infection, or multiorgan failure, due to the prolonged wait for a heart. These higher-risk patients are prone to longer lengths of stay, higher complication rates after VAD implantation, more postoperative infections, and a higher rate of perioperative right-VAD support. In addition, the proportion of urgent transplants (for patients on inotropic support, intra-aortic balloon pumps, etc.) has increased in the U.K. Today, 60% of heart transplantations are urgent cases, rather than the previous 20%. This translates to transplantations for sicker patients, resulting in worse outcomes. Furthermore, because of the donor-heart shortage, most U.K. centers are using more marginal donors, which further compromises transplant outcomes. Bridge-to-transplantation patients are younger than destination-therapy patients, but the body mass index of patients accepted for bridge to transplantation is limited to the body mass index in the donor pool. Finally, since referral for left-VAD implantation is often delayed until patients deteriorate, there is increased use of short-term support devices prior to the implantation of long-term devices. Wider Use of Ventricular Assist Devices In the U.S., the indications are for bridge to transplantation or destination therapy, which fosters more appropriate timing of implantation to meet the patient's clinical need. The main limitation to wider use of VADs in many European countries is cost. To determine the coverage of high-technology therapies, funding bodies in Europe closely evaluate the cost per Quality-Adjusted Life Years (QALY) gained. Demonstration of a reduced cost per QALY would encourage European governments to fund more devices and to expand the destination-therapy indication. In the Netherlands, there is only bridge-to-transplantation funding, but the number of bridge-to-transplantation implants is not capped by the number of transplants—hence, it does not limit patient care so much. Differences in Transplantation The trend toward decreased heart transplantation is more noticeable in Europe than in the U.S. Although the numbers of donors have decreased everywhere, they are decreasing more in Europe, as indicated by the more dramatic decline in transplants (Fig. 1).1 Furthermore, the proportion of younger donors is still higher in the U.S. (Fig. 2).1 In Europe, there is a higher proportion of older donors with poor organ quality, due to the lower number of traumatic deaths in young people—which in turn can be explained by the European use of seat belts, speed cameras, crash helmets, etc. In the U.S., the recipient age is higher and the donor age lower. Recently, non-heart-beating lung donation has been introduced in some countries; it may be that relatives prefer this option, and hearts are being lost as a consequence. Fig. 1 Number of heart transplants per year in Europe, North America, and elsewhere. Fig. 2 Donor age distribution in Europe, North America, and elsewhere. Myocardial Recovery The approach to myocardial recovery is also affected by the 2 different systems. In bridge-to-transplantation-only funded programs, some governments, such as that of the U.K., initially refused to fund a patient's implant once the myocardium recovered, stating that the funding was for bridge to transplantation only. However, after the first few VADs were explanted, the U.K. changed this policy. The advent of myocardial recovery after VAD support then prompted the U.K. to increase its cap on bridge-to-transplantation devices, but the number of devices funded is still less than the number of transplants performed annually. In the U.S., the challenges to promoting recovery are different. First, the proportion of ischemic heart disease patients receiving VADs is higher, and these patients are less likely to recover; and second, cost limits the number of diagnostic tests that can be performed on patients who receive VADs—so their recovery is more difficult to evaluate. Third, it is more difficult in the U.S. to study investigational drugs in combination with investigational VADs, in order to promote recovery. Destination therapy removes the pressure to transplant, but VAD programs might suffer financially because hospitals lose the profit margin associated with heart transplantation. Finally, destination therapy enables VAD implantation to be independent of heart transplantation, and we are nearing the point where VADs are becoming the primary alternative to transplantation. However, the growing population of VAD patients will render even more important the need of a rescue strategy for the few patients who develop life-threatening complications from their VADs. The best bailout for these patients will be transplantation; hence, the number of transplants will once again become an important rate-limiting factor for each program.