Advanced heart failure: Transplantation, LVADs, and beyond

CARDIAC TRANSPLANTATION: SUCCESSES, CHALLENGES

Survival rates after heart transplantation are now excellent. The 1-year survival rate is about 90%, the 5-year rate is about 70%, but only about 20% survive 20 years or longer.^8,9 The prognosis is not as good as for combined heart-lung transplantation patients.

Age is an important factor and is a contentious issue: some medical centers will not offer transplantation to patients over age 65. Others regard age as just another risk factor, like renal dysfunction or diabetes.

Quality of life after heart transplantation is excellent: patients are usually able to return to work, regardless of their profession.

The leading cause of death after heart transplantation is malignancy, followed by coronary artery vasculopathy, then by graft failure. Some patients develop left ventricular dysfunction and heart failure of unknown cause. Others develop antibody-mediated rejection; in recent years this has been more promptly recognized, but treatment remains a challenge.

Acute rejection, which used to be one of the main causes of death, now has an extremely low incidence because of modern drug therapies. In a US observational study currently being conducted in about 200 patients receiving a heart transplant (details on CTOT-05 at www.clinicaltrials.gov), the incidence of moderate rejection during the first year is less than 10% (Starling RC, unpublished observation). But several concerns remain.

Adverse effects of immunosuppressive drugs continue to be problematic. These include infection, malignancy, osteoporosis, chronic kidney toxicity, hypertension, and neuropathy.

Renal dysfunction is one of the largest issues. About 10% of heart transplant recipients develop stage 4 kidney disease (with a glomerular filtration rate < 30 mL/min) and need kidney transplantation or renal replacement therapy because of the use of calcineurin inhibitors for immunosuppression.¹⁰

Coronary artery vasculopathy was the largest problem when heart transplantation began and continues to be a major concern and focus of research.^11,12 Case 1 (below) is an example of the problem.

Case 1: Poor outcome despite an ideal scenario

A 57-year-old businessman had dilated cardiomyopathy and progressive heart failure for 10 years. He was listed for transplantation in 2008 and was given an LVAD (HeartMate II, Thoratec Corp, Pleasanton, CA) as a bridge until a donor heart became available.

In 2009, he received a heart transplant under ideal conditions: the donor was a large 30-year-old man who died of a gunshot wound to the head in the same city in which the patient and transplant hospital were located. Cardiopulmonary resuscitation was not performed, and the cold ischemic time was just a little more than 3 hours. Immune indicators were ideal with a negative prospective cross-match.

Laboratory results after transplantation included creatinine 1.7 mg/dL (normal 0.6–1.2 mg/dL), low-density lipoprotein cholesterol 75 mg/dL, high-density lipoprotein cholesterol 64 mg/dL, and triglycerides 90 mg/dL.

The patient was given immunosuppressive therapy with cyclosporine (Neoral), mycophenolate (CellCept), and prednisone. Because his creatinine level was high, he was also perioperatively given basiliximab (Simulect), a monoclonal antibody to the alpha chain (CD25) of the interleukin-2 receptor. (In a patient who has poor renal function, basilixumab may help by enabling us to delay the use of calcineurin inhibitors.) He also received simvastatin (Zocor) 10 mg.

Per Cleveland Clinic protocol, he underwent 13 biopsy procedures during his first year, and each was normal (grade 0 or 1R). Evaluation by cardiac catheterization at 1 year showed some irregularities in the left anterior descending artery, but a stent was not deemed necessary. Also, per protocol, he underwent intravascular ultrasonography, which revealed abnormal thickness in the intima and media, indicating that coronary artery disease was developing, although it was nonobstructive.

Two months after this checkup, the patient collapsed and suddenly died while shopping. At autopsy, his left anterior descending artery was found to be severely obstructed.

Coronary artery vasculopathy is still a major problem

This case shows that coronary artery vasculopathy may develop despite an ideal transplantation scenario. It remains a large concern and a focus of research.

Coronary vasculopathy develops in 30% to 40% of heart transplant recipients within 5 years, and the incidence has not been reduced by much over the years. However, probably fewer than 5% of these patients die or even need bypass surgery or stenting, and the problem is managed the same as native atherosclerosis. We perform routine annual cardiac catheterizations or stress tests, or both, and place stents in severely blocked arteries.

THE DONOR SHORTAGE: CHANGING HOW HEARTS ARE ALLOCATED

The number of patients receiving a heart transplant in the United States—about 2,000 per year—has not increased in the past decade. The European Union also has great difficulty obtaining hearts for people in need, and almost every transplant candidate there gets mechanical support for some time. The gap between those listed for transplant and the number transplanted each year continues to widen in both the United States and Europe.

All transplant candidates are assigned a status by the United Network of Organ Sharing (UNOS) based on their medical condition. The highest status, 1A, goes to patients who are seriously ill, in the hospital, on high doses of inotropic drugs (specific dosages are defined) and mechanical circulatory support such as an LVAD, and expected to live less than 1 month without a transplant. Status 1B patients are stable on lower-dose inotropic therapy or on mechanical support, and can be in the hospital or at home. Status 2 patients are stable and ambulatory and are not on inotropic drugs.

In July 2006, UNOS changed the rules on how patients are prioritized for obtaining an organ. The new rules are based both on severity of illness (see above) and geographic proximity to the donor heart—local, within 500 miles (“zone A”) or within 500 to 1,000 miles (“zone B”). The order of priority for donor hearts is:

• Local, status 1A
• Local, status 1B
• Zone A, status 1A
• Zone A, status 1B
• Local, status 2
• Zone B, status 1A
• Zone B, status 1B
• Zone A, status 2.

As a result of the change, donor hearts that become available in a particular hospital do not necessarily go to a patient in that state. Another result is that status 2 patients, who were previously the most common transplant recipients, now have much less access because all status 1 patients within 500 miles are given higher priority. Since the change, only 8% of hearts nationwide go to status 2 patients, which is 67% fewer than before. At the same time, organs allocated to status 1A patients have increased by 26%, and their death rates have fallen.³

The new allocation system is a positive change for the sickest patients, providing quicker access and a reduction in waiting-list mortality.¹³ The drawback is that status 2 patients who are less ill are less likely to ever receive an organ until their condition worsens.

Heart transplant outcomes are publicly reported

The Scientific Registry of Transplant Recipients publicly reports heart transplant outcomes (www.srtr.org). For any transplant center, the public can learn the number of patients waiting for a transplant, the death rate on the waiting list, the number of transplants performed in the previous 12 months, the waiting time in months, and observed and risk-adjusted expected survival rates. A center that deviates from the expected survival rates by 10% or more may be audited and could lose its certification.

Also listed on the Web site is the percentage of patients who receive a support device before receiving a transplant. This can vary widely between institutions and may reflect the organ availability at the transplant center (waiting times) or the preferences and expertise of the transplantation team. We believe that the mortality rate on the waiting list will be reduced with appropriate use of LVADs as a bridge to transplantation when indicated. We have now transitioned to the use of the improved continuous-flow LVADs and rarely maintain patients on continuous inotropic therapy at home to await a donor organ.