The epidemiologic magnitude of CHF is staggering. Approximately 5 million patients in the United States have CHF, and there are 500,000 new cases per year. It is estimated that CHF will develop in 20% of the population older than 40 years. Many patients who consult an ophthalmologist belong to the older age group that is particularly prone to this condition. Heart failure occurs when the heart cannot meet the metabolic demands of the tissues. The cardiac pump itself may be failing, or it may be nearly normal but unable to keep up with demand. The direct result of heart failure is circulatory failure.
Heart failure is classified into 4 stages, including stages for patients at risk for heart failure and those without current signs or symptoms (Fig 5-4). Symptomatic heart failure is subdivided according to ejection fraction (EF), which is the calculated proportion of blood ejected by the ventricle during a single or average contraction. The EF is more than 50% in an average person without HF. A left ventricular EF less than or equal to 40% is classified as heart failure with a reduced ejection fraction (HFrEF), and a patient in heart failure with an EF greater than 50% is classified as heart failure with a preserved ejection fraction (HFpEF). HFrEF is sometimes called left-sided, or systolic heart, failure, and HFpEF as right-sided, or diastolic, heart failure. Approximately two-thirds of all CHF is HFrEF, but HFpEF is more common in women.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.