Advanced heart failure: Transplantation, LVADs, and beyond

Patients with advanced heart failure far outnumber the hearts available for transplantation. Partly as a consequence of this shortage, left-ventricular assist devices (LVADs) are being used more widely.

This article is an update on options for managing severe, advanced heart failure, with special attention to new developments and continuing challenges in heart transplantation and LVADs.

THE PREVALENCE OF HEART FAILURE

About 2.6% of the US population age 20 and older have heart failure—some 5.8 million people. Of these, about half have systolic heart failure.¹ Patients with systolic heart failure can be classified by degree of severity under two systems:

The New York Heart Association (NYHA) classifies patients by their functional status, from I (no limitation in activities) to IV (symptoms at rest). NYHA class III (symptoms with minimal exertion) is sometimes further broken down into IIIa and IIIb, with the latter defined as having a recent history of dyspnea at rest.

The joint American College of Cardiology and American Heart Association (ACC/AHA) classification uses four stages, from A (high risk of developing heart failure, ie, having risk factors such as family history of heart disease, hypertension, or diabetes) to D (advanced heart disease despite treatment). Patients in stage D tend to be recurrently hospitalized despite cardiac resynchronization therapy and drug therapy, and they cannot be safely discharged without specialized interventions. The options for these patients are limited: either end-of-life care or extraordinary measures such as heart transplantation, long-term treatment with inotropic drugs, permanent mechanical circulatory support, or experimental therapies.²

The estimated number of people in ACC/AHA stage D or NYHA class IV is 15,600 to 156,000. The approximate number of heart transplants performed in the United States each year is 2,100.³

WHICH AMBULATORY PATIENTS ARE MOST AT RISK?

The range for the estimated number of patients with advanced heart failure (NYHA class IIIb or IV) is wide (see above) because these patients may be hard to recognize. The most debilitated patients are obvious: they tend to be in the intensive care unit with end-organ failure. However, it is a challenge to recognize patients at extremely high risk who are still ambulatory.

The European Society of Cardiology⁴ developed a definition of advanced chronic heart failure that can help identify patients who are candidates for the transplant list and for an LVAD. All the following features must be present despite optimal therapy that includes diuretics, inhibitors of the renin-angiotensin-aldosterone system, and beta-blockers, unless these are poorly tolerated or contraindicated, and cardiac resynchronization therapy if indicated:

• Severe symptoms, with dyspnea or fatigue at rest or with minimal exertion (NYHA class III or IV)
• Episodes of fluid retention (pulmonary or systemic congestion, peripheral edema) or of reduced cardiac output at rest (peripheral hypoperfusion)
• Objective evidence of severe cardiac dysfunction (at least one of the following): left ventricular ejection fraction less than 30%, pseudonormal or restrictive mitral inflow pattern on Doppler echocardiography, high left or right ventricular filling pressure (or both left and right filling pressures), and elevated B-type natriuretic peptides
• Severely impaired functional capacity demonstrated by one of the following: inability to exercise, 6-minute walk test distance less than 300 m (or less in women or patients who are age 75 and older), or peak oxygen intake less than 12 to 14 mL/kg/min
• One or more hospitalizations for heart failure in the past 6 months.

Treadmill exercise time is an easily performed test. Hsich et al⁵ found that the longer patients can walk, the lower their risk of death, and that this variable is about as predictive of survival in patients with systolic left ventricular dysfunction as peak oxygen consumption, which is much more cumbersome to measure.

The Seattle Heart Failure Model gives an estimate of prognosis for ambulatory patients with advanced heart failure. Available at https://depts.washington.edu/shfm/, it is based on age, sex, NYHA class, weight, ejection fraction, blood pressure, medications, a few laboratory values, and other clinical information. The model has been validated in numerous cohorts,⁶ but it may underestimate risk and is currently being tested in clinical trials (REVIVE-IT and ROADMAP; see at www.clinicaltrials.gov).

Recurrent hospitalization is a simple predictor of risk. A study of about 7,000 patients worldwide found that after hospitalization with acute decompensated heart failure, the strongest predictor of death within 6 months was readmission for any reason within 30 days of the index hospitalization (Starling RC, unpublished observation, 2011). Any patient with heart failure who is repeatedly hospitalized should have a consultation with a heart failure specialist.

INOTROPIC THERAPY FOR BRIDGING

Inotropic drugs, which include intravenous dobutamine (Dobutrex) and milrinone (Primacor), are used to help maintain end-organ function until a patient can obtain a heart transplant or LVAD.

Inotropic therapy should not be viewed as an alternative to heart transplantation or device implantation. We inform patients that inotropic therapy is purely palliative and may actually increase the risk of death, which is about 50% at 6 months and nearly 100% at 1 year. A patient on inotropic therapy who is not a candidate for a transplant or for an assist device should be referred to a hospice program.⁷