William Chancellor and Leora Yarboro
This chapter is a revision and update of that included in previous editions of the TSRA Review written by Walter F. DeNino (2nd edition) and Stephen H. McKellar (1st edition).
Heart failure is a clinical syndrome wherein one or both ventricles are unable to either completely fill during diastole or adequately eject blood during systole resulting in congestive symptoms and decreased end organ perfusion. It affects greater than 23,000,000 patients worldwide, including an estimated 5,700,000 Americans, and its prevalence is increasing in developed countries due to the aging population and improved therapies for early-stage disease.
Pathophysiology
The most common cause of heart failure is myocardial ischemia secondary to coronary artery disease. It can present acutely after myocardial infarction or as hibernating myocardium with contractile abnormalities due to chronic ischemia. Non-ischemic etiologies include congenital heart disease, valvulopathy, substance abuse, idiopathic dilated cardiomyopathy, peripartum cardiomyopathy, and restrictive or infiltrative processes such as hypertrophic obstructive cardiomyopathy, amyloidosis, or sarcoidosis. Patients are broadly classified as having heart failure with reduced left ventricular ejection fraction (HFrEF), also known as systolic heart failure, or heart failure with preserved ejection fraction (HFpEF) otherwise known as diastolic heart failure.
Clinical presentation
Symptoms include dyspnea, fatigue, and exercise intolerance that often go unnoticed due to their insidious onset. Patients may then progress to unintentional weight loss or fluid retention exhibited by pulmonary congestion, peripheral edema, and ascites. Advanced heart failure may present as new onset arrhythmia or cardiogenic shock. The etiology will also determine the acuity of the initial presentation. The most striking example is acute cardiogenic shock following large territory MI.
Diagnosis
The diagnosis of heart failure is predominately clinical and based on signs and symptoms elicited during a thorough history and physical exam. Common physical exam findings include pedal edema, elevated jugular venous pressure, displaced apical impulse, and S3 gallop. Further workup includes labs to evaluate renal and hepatic function as well as serum sodium, albumin, and B-type natriuretic peptide (BNP) or N-terminal pro-BNP (NT-proBNP). Electrocardiogram may show evidence of ischemia or prior MI but there are no abnormalities that are specific to the diagnosis of heart failure. Patients will frequently present with new onset atrial or ventricular arrhythmia. Chest radiograph is useful to assess the presence and degree of pulmonary edema, pleural effusions, or pulmonary vascular congestion. Echocardiography is a mainstay of heart failure diagnosis as it can be used to evaluate systolic and diastolic function. It is readily available and allows for serial observation to track progression of ventricular dysfunction over time. When advanced heart failure is suspected patients should be evaluated with right heart catheterization to document filling pressures and cardiac index. Finally, exercise testing should be performed to determine functional capacity and VO2 max. Patients are stratified based on the severity of their symptoms according to the New York Heart Associated classification. The diagnosis of advanced heart failure is made when there are objective findings of cardiac dysfunction such as LVEF <30%, elevated filling pressures, left atrial distension, pulmonary artery hypertension, or peak VO2 <14kg/min and severe impairment of functional capacity (NYHA class III or IV) with fluid retention, hypotension, or arrhythmia despite optimal medical therapy (OMT) and appropriate device therapy.
Treatment
Medical therapy
Pharmacologic therapy has been shown to improve symptoms, slow deterioration, and reduced mortality in patients with congestive heart failure. First-line medical therapy includes an angiotensin system inhibitor, ß-blocker, and diuretic. Refractory symptoms warrant trialing an alternative angiotensin system inhibitor, hydralazine-nitrate, digoxin, or mineralocorticoid receptor antagonists. Patients who remain symptomatic despite OMT may be candidates for chronic intravenous inotropes or vasodilators. Cardiac resynchronization therapy, with or without an implanted cardiac defibrillator, is recommended for NYHA II-IV symptoms with a left bundle branch pattern, QRS width ≥130 msec, and LVEF <35%.
Surgical therapy
Heart transplantation remains the gold standard for surgical management of end-stage heart failure but it continues to be limited by the shortage of organ donors relative to the increasing number of potential recipients. For patients who present in acute cardiogenic shock there are a number short-term mechanical circulatory support (MCS) devices that can augment ventricular function while a causative lesion is identified and treated or a decision is made about proceeding with heart transplantation or longer term MCS. The use of long term MCS has rapidly expanded due to improvements in left ventricular assist device (LVAD) technology. Classically, indications for MCS are as a bridge to transplantation (BTT) for eligible patients, bridge to decision (BTD) if eligibility is still being determined, or as destination therapy (DT) for transplant ineligible patients. Percutaneous therapies and temporary implanted devices can be used as a bridge to recovery (BTR) from an acute insult causing cardiogenic shock. Recent changes in organ allocation policies have had a dramatic impact on implant strategy since their implementation in 2018. Under the new policy, patients requiring ECMO or other non-dischargeable mechanical support are given preference in order to decrease waitlist mortality. As a result, greater than 70% of LVADs placed since the policy changes took effect have been for DT.
Indications for short-term mechanical circulatory support include cardiac arrest, myocardial infarction, post-cardiotomy shock, acute myocarditis or cardiomyopathy, high-risk coronary intervention, or refractory arrhythmia. They are typically considered a BTR or BTD. The most commonly used short-term MCS devices are the intra aortic balloon pump, percutaneous ventricular assist devices such as the Impella or TandemHeart, and VA ECMO. There is limited data to recommend one device over the other so the decision is based on indication, availability, and intended duration of support. Contraindications to MCS include irreversible neurologic injury, systemic illness limiting survival, disseminated malignancy, severe peripheral vascular disease, and contraindications to anticoagulation.
Indications for long term MCS include advanced heart failure that is refractory to OMT and causing poor quality of life, end-organ dysfunction, inotrope dependence, cachexia, low aerobic activity (peak VO2<14mL/kg/min), or 6-minute walk distance <300 meters. These patients should be referred to a heart failure specialist and considered for heart transplant and LVAD concurrently. The decision to proceed with LVAD therapy must be agreed upon by a multidisciplinary heart team and it is imperative that patients have adequate social support outside of the hospital. Prior to LVAD implantation carefully review echocardiography for the presence of valvular insufficiency, a patent foramen ovale, or a ventricular septal defect. Consideration should be given to aortic valve replacement and mitral or tricuspid valve repair as appropriate. Special attention should be given to right ventricular function as right-sided heart failure occurs in 20-35% of patients after LVAD and may be predicted by abnormal CVP or RV stroke work index. Temporary right ventricular assist device placement has been shown to improve short and long-term outcomes in patients at risk for RV failure after LVAD.
First generation left ventricular assist devices provided pulsatile flow and they were shown to decrease mortality among patients awaiting heart transplantation in retrospective analyses. These findings led to the landmark REMATCH trial, which compared a first-generation LVAD (HeartMate XVE) to OMT in patients not eligible for transplant. REMATCH demonstrated a significant survival benefit leading to LVAD approval for DT as well as BTT. Refinements to LVAD design yielded a second-generation continuous axial-flow device (HeartMate II) that could be made smaller and more durable because it required fewer moving parts. Further refinements lead to the development of the centrifugal flow HeartWare HVAD and HeartMate 3. As of the time of this writing the HeartMate II, HVAD, and HeartMate 3 are the only devices commercially available in the United States.
Survival after implantation of continuous flow LVADs exceeds 80% at 1 year and 70% at 2 years, which is comparable to heart transplant outcomes at similar time points. Patients managed as BTT have higher survival than DT and 61% of BTT undergo transplantation by 3 years. The most common complications are GI bleeding, stroke, infection, and right heart failure. Bleeding after placement of a continuous flow device is multifactorial. Continuous flow causes the development of arteriovenous malformations on mucosal surfaces and the interface of blood and LVAD components induces coagulopathy. These factors, coupled with the need for anticoagulation, explain why GI bleeding occurs in 15-20% of patients in the first year. Efforts to reduce anticoagulation must be balanced with the risk of stroke and pump thrombosis. However, the rate of pump thrombosis associated with the HeartMate 3 in the MOMENTUM 3 trial was exceedingly low and the rate of disabling stroke was 5% leading to speculation that lower INR goals may be possible and research efforts to determine the optimal anticoagulation strategy are ongoing.Infections are the most common adverse events, occurring in approximately 40% of LVAD patients in the first year but reports vary based on how the outcome is defined.Infections can be broadly defined as device specific (pump, cannula, pocket, driveline), device related (bloodstream, mediastinum), or non-device (respiratory, urinary tract). Driveline infections can usually be adequately treated with long-term suppressive antibiotics and the presence of an active driveline infection does not adversely affect outcomes of heart transplantation.
Suggested Readings
- Teuteberg JJ, Cleveland JC, Jr., Cowger J, et al. The Society of Thoracic Surgeons Intermacs 2019 Annual Report: The Changing Landscape of Devices and Indications. Ann Thorac Surg. 2020;109:649-660.
- Takeda K, Takayama H, Naka Y. Left Ventricular Assist Devices and Total Artificial Heart. In: Sellke FW, del Nido PJ,Swanson SJ, eds. Sabiston & Spencer Surgery of the Chest. 8th ed. Philadelphia: Saunders Elsevier; 2015:1701-1728.
- Rose EA, Gelijns AC, Moskowitz AJ, et al. Long-term use of a left ventricular assist device for end-stage heart failure. N Engl J Med. 2001;345:1435-1443.
- Mehra MR, Goldstein DJ, Uriel N, et al. Two-Year Outcomes with a Magnetically Levitated Cardiac Pump in Heart Failure. N Engl J Med. 2018;378:1386-1395.
