Description

Heart failure (HF) results from inability of the heart to fill and/or pump blood sufficiently to meet tissue metabolic needs. Occurs when adequate cardiac output can be achieved only at the expense of elevated filling pressures. It is the principal complication of heart disease. For acute HF, see “Heart Failure, Acutely Decompensated.” HF is the preferred term to congestive HF as patients are not always congested (fluid overloaded).

• Can involve the left heart, the right heart, or be biventricular. It is progressive and manifested by remodeling (altered heart anatomy). The AHA/ACC uses a staging system to delineate the one-way progression of HF: stage A: at risk for HF, no structural disease; stage B: structural disease, no HF symptoms; stage C: structural disease, HF symptoms; stage D: end-stage disease.
• The New York Heart Association (NYHA) classification is a subjective grading scale used for classifying a patient’s functional status: NYHA I: asymptomatic; NYHA II: symptomatic with moderate exertion; NYHA III: symptomatic with mild exertion and may limit activities of daily living; NYHA IV: symptomatic at rest.

Epidemiology

HF accounts for close to 1 million hospitalizations a year, with 25% readmission in 30 days.

Incidence
In the United States, 550,000 new cases are diagnosed annually with >250,000 deaths/year. Incidence in the US is stable; however, incidence of HF with preserved ejection fraction (HFpEF) continues to rise accounting for 50% of HF cases (1).

Prevalence
Estimated 23 million individuals have HF worldwide. ~6.5 million people in the United States have HF; <1% in those age <50 years, increasing to 10% of those age >80 years. Primarily a disease of the elderly; 75% of hospital admissions for HF are for persons >65 years of age.

Etiology and Pathophysiology

• Two physiologic components explain the clinical findings of HF and result in four categories:
  • HF with reduced ejection fraction (HFrEF): an inotropic abnormality, often from myocardial infarction (MI) or dilated cardiomyopathy (CM), resulting in diminished systolic emptying (EF ≤40%)
  • HF with mildly reduced EF (HFmrEF): mild systolic dysfunction with EF of 41–49%, clinically behaves like HFpEF
  • HF with improved EF (HFimpEF): previously HFrEF, with improvement in systolic function now EF >40%
  • HFpEF: a compliance abnormality, often due to hypertensive CM, in which the ventricular relaxation is impaired (EF ≥50%)
• Most common etiologies: coronary artery disease (CAD)/MI and hypertension (HTN). Others include the following:
  • Myocarditis and CM: alcoholic, viral, drugs, muscular dystrophy, infiltrative (e.g., amyloidosis, sarcoidosis), postpartum, infectious (e.g., Chagas disease, HIV), hypertrophic CM (HCM), inherited familial dilated CM
  • Valvular and vascular abnormalities: valvular stenosis or regurgitation, rheumatic heart; renal artery stenosis, usually bilateral, may cause recurrent “flash” pulmonary edema.
  • Chronic lung disease and pulmonary HTN
  • Arrhythmias: atrial fibrillation (AFib), other tachyarrhythmias, high-grade heart block, frequent PVCs
  • Other: high-output states: hyperthyroidism, anemia; cardiac depressants (β-blocker overdose), stress induced; iatrogenic volume overload (extreme overload in patients with normal hearts and kidneys); idiopathic: 20–50% of idiopathic dilated CM are familial.

Genetics
Multiple genetic abnormalities responsible for a variety of phenotypes have been identified. Consider genetic screening for first-degree relatives of HCM and arrhythmogenic RV dysplasia.

Risk Factors

CAD/MI, HTN, valvular heart disease, diabetes, cardiotoxic medications, obesity, older age

General Prevention

Control HTN and other risk factors.