In this large retrospective study examining the use of ventricular assist devices in the Medicare population, we found that patients receiving an assist device had prolonged index hospitalizations and high perioperative mortality, a high likelihood of readmission within 6 months, and a resulting high cost of inpatient care. The analysis included all Medicare fee-for-service beneficiaries, so it provides a complete picture of the use of ventricular assist devices beyond clinical trial settings alone. Our findings highlight the importance of the perioperative clinical course for long-term mortality and morbidity.
Mechanical ventricular assistance is a challenging technology to assess, in part because patients with heart failure are already at high risk of mortality and readmission. Among Medicare beneficiaries with heart failure, mortality is 27% and the readmission rate is 65% at 1 year.11
Patients with heart failure, especially those with end-stage heart failure, incur high medical costs.12,13
Mortality among patients with severe heart failure and who are inotrope-dependent is over 75% at 1 year,14
and mortality approaches 100% among those who undergo cardiac surgery and can not be weaned from cardiopulmonary bypass. Moreover, among all patients receiving medical therapy in trials of assist devices as destination therapy, survival is less than 25% at 1 year.4,15
Although REMATCH and other studies found that ventricular assist devices improve mortality compared with medical therapy,4,15
uncertainty remains regarding their routine use. In 2004, a National Heart, Lung, and Blood Institute working group established a goal of 50% survival at 2 years and minimal time in the hospital after device implantation as a prerequisite for widespread adoption of assist devices as destination therapy.16
Although experience with the devices has improved with device evolution,17,18
overall outcomes in the Medicare population have not met this goal. Continued postmarketing surveillance will be essential as the use of assist devices expands to populations outside clinical trials, which tend to include patients who are older and sicker than patients in research settings.19–21
Another goal in the use of ventricular assist devices is improved quality of life, which in part assumes reduced inpatient hospital days. Previous studies have shown improved quality of life for patients with ventricular assist devices, but the results were limited to small samples due to overall mortality rates.14
Thus, number of days in the hospital has become a surrogate measure for quality of life. For example, inotrope-dependent patients in REMATCH who were randomly assigned to receive a left ventricular assist device had a median of 255 days out of the hospital, compared with 105 days for patients assigned to medical therapy. Although a substantial number of patients who were discharged alive in the present study were readmitted within the first year, the average number of inpatient days was less than 30 during the following 2 years. There was a trend of increasing initial length of stay from a median of 18 days to 30 days or more. This trend warrants further attention and may become a basis for the development of new processes of care to reduce length of stay and costs. Number of days in the hospital could also be considered as a global ranking endpoint in future studies, because it captures key elements of the clinical course involving this unique patient population.22
We also examined inpatient costs associated with ventricular assist devices. Mean Medicare payments for inpatient costs at 1 year after implantation were $178 714 in the primary device group and $111 769 in the postcardiotomy group. The costs are comparable to or lower than costs associated with liver transplantation.23
These estimates do not include costs for skilled nursing, outpatient visits, medications, home health care, physical and occupational therapy, and durable medical equipment, but they do include costs for subsequent hospitalizations, including hospitalizations for heart transplantation and device removal. Although the cost of ventricular assist devices in the Medicare population will be relatively high, Medicare administrators have suggested that payments for innovative technology may spur investment, particularly in areas with otherwise limited therapeutic alternatives or significant market barriers.24
Although other studies have found improved outcomes over time in postcardiotomy patients with ventricular assist devices, we did not observe this trend among Medicare beneficiaries.2
For unknown reasons, 1-year survival from 2000 through 2006 for these patients declined significantly from 41% to 22%. A potential explanation is that patients’ risk profiles may have shifted, so that patients who previously would not have been considered for an assist device are now undergoing salvage therapy.25
Also, the increasing availability of ventricular assist devices for salvage therapy in patients undergoing complicated cardiac surgery may allow opportunities for use of the devices that were previously unavailable. It is important to note that previous work focused on operative mortality from 1995 through 2004; the study populations were younger and other patient characteristics differed from this study. Future studies should examine what factors are contributing to the trends in outcomes we observed.
Improving outcomes will require a focus on the high perioperative mortality found in this and other studies.4,15
Identifying patients who are likely to benefit from assist devices and excluding those whose likelihood of survival is low is warranted.2,26
Because we found a volume-outcome relationship between device implantation and mortality in the postcardiotomy group, development of systems that foster the transfer of these patients to experienced centers may improve outcomes.27,28
In addition, there appears to be a trend toward improved outcomes in high-volume centers in the primary device cohort. Other studies have suggested that complex procedures should be concentrated at centers that are likely to translate early experience into acceptable outcomes.28,29
Moreover, our observation of 65% survival at 2 years among patients discharged alive warrants further clinical investigation to identify factors associated with survival. These findings support a 2008 National Heart, Lung, and Blood Institute working group recommendation to conduct a randomized trial of ventricular assist devices in patients who have not developed serious complications of heart failure.30
Our study has some limitations. Medicare claims do not include clinical details about the type of device and site of implantation, so we had limited ability to determine the indication or identify important clinical variables associated with mortality. However, in a sensitivity analysis using data from 2005 and 2006, outcomes of patients receiving implantable versus non-implantable devices were similar to outcomes for patients in the primary device and postcardiotomy groups. Most devices implanted during the study period were pulsatile devices, and we were unable to distinguish patients with continuous-flow devices who were enrolled in a clinical trial. In addition, the analysis included only patients enrolled in fee-for-service Medicare, so other patients are not represented in the study. Although the primary aim of the study was to examine outcomes of Medicare beneficiaries, outcomes may differ because of patients’ age or comorbidity as compared with other patient populations. However, selection bias is likely to be minimal because the study included all Medicare fee-for-service beneficiaries and all hospitals that implanted a ventricular assist device in a Medicare beneficiary.