Cardiac Case Study: April 2008

Cardiac Case Study: April 2008

LVAD Therapy Offers a Successful Alternative for End-Stage Heart Failure

By S. Raja Laskar, MD, Assistant Professor of Internal Medicine, Division of Cardiology, Center for Heart Failure Therapy and Transplantation, Emory University School of Medicine

Heart failure is increasing in incidence and prevalence in America. It is estimated 5 million people in the United States have congestive heart failure. Of that 5 million, almost 100,000 patients have advanced, end-stage heart failure or stage D heart failure.1 This group is the most expensive and difficult to treat. Stage D patients are the ones most likely to require recurrent hospitalizations for decompensated heart failure.2 The number of patients with stage D heart failure is expected to continue to increase given the success of medical therapy and device therapies for heart failure such as biventricular pacemakers and implantable defibrillators.

Despite advances in the treatment of patients with congestive heart failure, the survival of patients with stage D heart failure remains quite dismal. Although end-stage heart failure is difficult to define, a number of clinical factors help identify patients with end-stage heart failure. These clinical factors include hyponatremia, renal insufficiency and consistently low systolic blood pressure.3 No definitive clinical risk score has been developed to identify end-stage heart failure. However, patients who are unable to be weaned from inotropic support by definition have a very poor survival rate. Patients who are on continuous palliative inotropes have a six-month mortality between 60 percent and 75 percent.4 Treatment options for end-stage heart failure are limited to palliation, cardiac transplantation and left ventricular assist device (LVAD) implantation. Cardiac transplantation is definitive therapy for end-stage heart failure with excellent one- and five-year survival rates (one-year rate is 87 percent and five-year rate is 70 percent).5 Unfortunately, the number of cardiac transplants performed in the United States is limited to approximately 2,200 due to donor availability.

long term survival rate

Alternative treatment options are available to selected patients who are not suitable candidates for transplantation or who need a bridge to transplant if a suitable donor is not available for urgent transplantation. LVADs have been in use for more than 25 years, primarily to support patients with refractory heart failure who are awaiting heart transplantation. Despite the severe nature of their illnesses, 70 percent to 80 percent of these patients will survive to transplantation.6 LVAD therapy for end-stage heart failure in patients not eligible for heart transplant was tested in the REMATCH clinical trial. In this landmark study, the only prospective, randomized study of LVAD versus medical therapy, LVAD therapy was compared to optimal medical therapy. At one year, survival was significantly better in those patients receiving an LVAD compared to those patients receiving the medical therapy only (52 percent versus 25 percent). Based on these results, the HeartMate XVE was approved by the FDA as “destination therapy” for end-stage heart failure for patients who are not transplant candidates.7 A registry has been maintained to monitor the morbidity and mortality of patients who have received the HeartMate XVE for destination therapy. The survival of patients in this registry is 31 percent at two years.8

The HeartMate XVE has significant limitations, however, as a long-term device. It is a large device so recipients need to have a large body habitus to accommodate it. In some patients who require long-term support, the audible nature of the LVAD is a potential source of discomfort. The HeartMate II is an investigational LVAD currently being studied for both bridge to transplantation and destination therapy. It is a continuous axial rotary pump.

Heartmate II LVAD

Like the HeartMate XVE, the HeartMate II uses an inflow cannula, which connects the device to the apex of the left ventricle and a cannula that connects the device to the ascending aorta. The pump is an internal motor with helical blades that pumps blood continuously into the ascending aorta. It can provide up to 10 liters of cardiac output. The speed of the pump, which can be adjusted, determines the cardiac output provided from the device. The potential advantages of the device provides an expanded patient population due to the small nature of the device. In addition, it is expected the device will have increased mechanical reliability because there is only one moving part — the internal rotor.9

A 32-year-old man with long-standing heart failure was referred to Emory for ventricular assist device implantation for end-stage heart failure. He originally was diagnosed with a dilated cardiomyopathy from viral myocarditis in 1997. He had maintained clinical stability for a number of years but exhibited progressive heart failure symptoms, despite aggressive medical therapy and biventricular pacemaker implantation. He eventually required inotropic support, and despite multiple attempts, he was unable to be weaned from inotropic therapy. He was evaluated for heart transplantation at an outside institution. Despite his young age, he was not a transplant candidate because of his obesity and inability to lose weight.

On his initial Clinic visit, the patient had a blood pressure reading of 72/52 and a heart rate of 100. He had evidence of moderate volume overload with an estimated JVP of 14cm and an audible S3. His body mass index (BMI) was estimated to be 39, and he was significantly above our established weight criteria for heart transplantation. On laboratory examination, he had a serum sodium of 128 meQ/l and a serum creatinine of 1.1 mg/dL. He was admitted to Emory University Hospital for further evaluation and intravenous diuresis. An echocardiogram revealed a markedly enlarged left ventricle with an LVED of 8.8 and an LVEF of 10 percent. He also had a dilated right ventricle with depressed function.

The patient was started on IV diuretics and underwent a right heart catheterization, which confirmed his marginal hemodynamics. At the time of his right heart catheterization, the patient had a pulmonary capillary wedge pressure (PCWP) of 26mmHg and a cardiac index of 1.6 while on inotropic therapy. We performed a multidisciplinary evaluation, including psychiatric, financial and social work consultation, to assess his candidacy for long-term mechanical support. After a lengthy discussion with the patient and his family, the patient enrolled in the HeartMate II study evaluating the HeartMate II device for end-stage heart failure. He was randomized to the HeartMate II device. He underwent a successful implantation of the device without significant peri-operative complications. He had an uneventful post-operative course and was discharged from the hospital after 20 days. He is now New York Heart Association (NYHA) Class I with minimal heart failure symptoms. He visits the heart failure clinic monthly for routine appointments. He currently is working part-time and attending school. We are hopeful he will lose weight so he will be a viable candidate for a heart transplant.

In 2008, Emory celebrated the 20-year anniversary of its heart transplant program and its 500th adult heart transplant. Emory’s cardiothoracic surgeons perform an average of 23 adult heart transplants each year and have a one-year post-transplant survival rate of 91 percent.

References:

  1. American Heart Association. Heart disease and stroke statistics — 2008 update. Dallas, TX: American Heart Association; 2008.
  2. Mackowiak J. Cost of the heart failure to the healthcare system.Am J Manage Care 1998; 4(suppl 6) S338-42.
  3. Aaronson KD, Schwartz JS, Chen TM, et al. Development and prospective validation of a clinical index to predict survival in ambulatory patients referred for cardiac transplant evaluation. Circulation 1997; 95:2660-2667.
  4. Hershberger RE, Nauman D, Walker T, et al. Care processes and clinical outcomes continuous outpatient inotropic support in patients with end-stage heart failure. J Card Fail 2003; 9:180-187.
  5. Taylor DO, Edwards LB, Boucek MM, et al. Registry of the International Society for Heart Lung Transplantation. JISHLT 2007; 26:769-781.
  6. Deng MC, Edwards LB, Hertz MI, et al. Mechanical circulatory support device database of the International Society of Heart and Lung Transplantation. 2005; 24:1182-87.
  7. Rose EA, Gellijins AC, Moscowitz AJ, et al. Long-term use of left ventricular assist device for end-stage heart failure. NEJM 2001; 345:1435-1443.
  8. Lietz K, Long JW, Khoury AJ, et al. Outcomes of long-term implantation of a left ventricular assist device for end-stage heart failure. Circulation 2007; 116:497-505.
  9. Miller LW, Pagani FD, Russell SD, et al. Use of a continuous flow device in patients awaiting heart transplantation. NEJM 2007; 357:885-896.

«« back to Cardiac Case Studies