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 over congestive HF as patients are not always congested (fluid overloaded).
• It involves the left heart, the right heart, or be biventricular. It is progressive—manifested by the remodeling (altered heart geometry) process. The American Heart Association/American College of Cardiology stages are a system to delineate the 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, approximately 25% readmitted within 30 days. The annual direct and indirect cost of HF in the United States is ~$34.4 billion.

Incidence
In the United States, 550,000 new cases are diagnosed annually with >250,000 deaths/year.

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) or systolic HF: an inotropic abnormality, often from myocardial infarction (MI) or dilated cardiomyopathy (CM), resulting in diminished systolic emptying (ejection fraction [EF] ≤40%)
  • HF with preserved EF (HFpEF) or diastolic HF: a compliance abnormality, often due to hypertensive CM, in which the ventricular relaxation is impaired (EF ≥50%)
  • 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%
• Most common etiologies: coronary artery disease (CAD)/MI and hypertension (HTN); others:
  • 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 [AF] and other tachyarrhythmias, high-grade heart block, frequent PVCs)
  • Others: 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.