Editor’s Note: Due to rapid changes with these technologies, this Fast Fact is meant to fully replace the first edition of #205 (‘Destination Ventricular Assist Devices for Heart Failure’ by Heather Ferris MD and Susan Hunt MD, published August 2008).

Introduction     About 250,000 Americans have end-stage heart failure, meaning they cannot carry out any physical activities without discomfort (dyspnea or angina) and are potentially eligible for advanced therapy such as transplantation. Less than 1% of patients, however, will receive a heart transplant. The left ventricular assist device (LVAD) was initially designed as an implanted mechanical circulatory support (MCS) to extend the life of patients awaiting heart transplants (“bridge-to-transplantation” (BTT)). In 2002, the FDA approved the LVAD not only as BTT, but also as “destination therapy” (DT) where the patient would keep the device for life, with no expectation of heart transplantation.

The Technology     Rapid growth in the types and numbers of MCS has occurred, including the development of the total artificial heart (see Fast Fact # 296) and biventricular support.  Basically, an LVAD involves surgical implantation of a pump to support cardiac output. Most often, this includes a conduit implanted in the left ventricle, and another into the aorta. Blood is pulled from the left ventricle, and mechanically moved into the aorta, increasing cardiac output and reducing heart failure symptoms. First generation LVADs did this with a pumping motion (pulsatile flow), but second generation LVADs move the blood continuously (continuous or axial flow). A third conduit (the driveline) passes from the pump through the abdominal wall, and attaches to the device’s battery and control system. This is of particular importance as serious life-threatening infections can result via the driveline.

Right and biventricular assist devices also exist, but are not currently approved for DT. DT patients can go home with their assist devices using a wearable battery system. Previously, to qualify for destination LVAD therapy, a patient needed to have severe, refractory Class IV heart failure including severe systolic dysfunction (ejection fraction <25%), inotrope dependence or very low peak oxygen consumption (<12 ml/kg/min), and sufficient body surface area to accommodate the LVAD. Now, patients with other situations are being considered (e.g., heart failure with preserved ejection fraction, congenital heart disease). Also, some advocate for expanding into patients who are less sick (Class IIIB) arguing that waiting to their heart failure is severe and refractory is too late, and raises their operative risk to unacceptably high levels. This hypothesis is currently being investigated.

Outcomes and Considerations

• In randomized studies, LVADs have shown significant mortality benefits,  with a 2-year survival of 58% for the newer continuous-flow devices compared to 24% with pulsatile flow LVADs and 8% with optimal medical therapy alone (1,2). Observational studies demonstrate 2-year survivals of 72%, but these databases are heterogeneous and patients may be healthier than the patients enrolled in the original randomized trials (3).
• Poorer survival is predicted by poor nutritional status (hypoalbuminemia), coagulopathy, baseline renal dysfunction, right heart dysfunction, and care at a less experienced MCS center (3,4). 
• Of those patients who are alive at 2 years, 79% will improve their NYHA functional class from class IV to class I, and health-related quality of life will improve by 178% (5). Readmission rates have reduced significantly as well (6).
• While markedly improved, continuous-flow LVADs have many potential complications including stroke (lifetime risk of 18%), infection (49%), sepsis (36%), bleeding requiring transfusion (81%), bleeding requiring surgery (30%), malfunctioning or thrombosed pump requiring pump replacement (10%), and readmission (94%) (2). Perioperative mortality has improved dramatically (often less than 10%) with improved patient selection and technology; however, palliative medicine providers and ICU staff often see MCS patients at their worst when critically ill or with a protracted, complicated recovery. This can be a source of moral distress, nevertheless many patients go on to perform all activities of daily living and have improved quality of life.
• MCS require a high degree of ongoing device care including daily self-care (e.g. controller self-tests, changing and maintaining power sources, and driveline exit site dressing changes), safety precautions (e.g. no emersion in water, showering with a shower kit, precautions while driving and traveling, need for a trained caregiver), and the ability to troubleshoot emergent MCS-related malfunction. Due to this, social stability and patient/family responsibility are key selection criteria when considering MCS implantation.

Discontinuing MCS and Advanced Care Planning    MCS may be implanted as BTT, but later become DT if patients are no longer transplant candidates. In the rare instance of myocardial recovery, some devices can be explanted. More often, MCS is removed at cardiac transplantation or, in the case of DT, when severe complications arise (such as pump thrombosis, mechanical pump failure etc).

MCS is a surgical therapy which can prolong life and improve function in appropriately selected patients, but can associated with significant morbidity, treatment burden, and mortality. Discussions with patients and surrogates to clarify prognosis, goals, and endpoints for MCS therapy should take place before implantation. These discussions should address the quality of life below which a patient would no longer want to continue MCS, and would want to initiate comfort focused only. Having open and honest discussion regarding goals of care prior to MCS is encouraged, and a suggested process for these discussions will be in a future Fast Fact. Practical aspects of discontinuing an LVAD in a dying patient are discussed in Fast Fact #269.

References

1. Rose EA, et al. Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) Study Group: long-term use of a left ventricular assist device for end-stage heart failure. N Engl J Med. 2001; 345:1435-1443.
2. Slaughter MS, et al. Advanced heart failure treated with continuous-flow left ventricular assist device. N Engl J Med. 2009; 361:2241-2251.
3. Kirklin JK, et al. Fifth INTERMACS annual report: risk factor analysis from more than 6,000 mechanical circulatory support patients. J Heart Lung Transplant. 2013; 32:141-56.
4. Cowger J, et al. Predicting survival in patients receiving continuous flow left ventricular assist devices: The HeartMate II Risk Score. J Am Coll Cardiol. 2013; 61: 313-21. Rogers JG, et al. Continuous flow left ventricular assist device improves functional capacity and quality of life of advanced heart failure patients. J Am Coll Cardiol. 2010; 55:1826-1834.
5. Rogers JG, et al. Continuous flow left ventricular assist device improves functional capacity and quality of life of advanced heart failure patients. J Am Coll Cardiol. 2010; 55:1826-1834.
6. Hasin T, et al. Readmissions after implantation of axial flow left ventricular assist device. J Am Coll Cardiol. 2013; 61:153-63.

Author Affiliations: Mayo Clinic, Rochester, MN (KMS); University of Colorado-Denver, Aurora, CO (DDM), University of Pittsburgh Medical Center, Pittsburgh, PA (HF); Health East Care System, St Paul, MN (SH).

Version History: Originally written by Heather Ferris MD and Susan Hunt MD, and published August 2008. Re-copy-edited in June 2009. Heavily rewritten to reflect new data, and republished in May 2013 as the 2nd Edition; copy-edited again in July 2015.