Heart Failure Indices And Their Role In Assessing Cardiac Health

Heart failure indices can be broadly or narrowly defined. The narrow definition, known as the cardiac index or CI, measures how many liters of blood the heart pumps per minute. This is essentially the product of heart rate and the volume of blood ejected with each beat. A lower index typically indicates more severe heart failure. However, while the cardiac index (often abbreviated as CO or CI in medical literature) is useful, it's not always the most practical parameter for everyday clinical use.

Commonly Used Diagnostic Markers For Heart Failure

Today, more commonly used tools for evaluating heart failure include echocardiographic measurements such as ejection fraction (EF), along with blood tests that measure levels of natriuretic peptides. Ejection fraction appears on cardiac ultrasound reports and represents the percentage of blood leaving the heart with each contraction. A normal EF ranges from 50% to 70%, with 60% ± 10% considered average. When EF drops below 40%, it's classified as reduced ejection fraction, indicating significant heart dysfunction. EF values above 50% are considered preserved, while values between 40% and 50% fall into the category of mid-range ejection fraction, suggesting a moderate level of heart failure.

Blood Biomarkers In Heart Failure Diagnosis

In addition to imaging, blood tests measuring B-type natriuretic peptide (BNP) or its precursor fragment NT-proBNP are essential in diagnosing and monitoring heart failure. Elevated levels of these peptides indicate increased stress on the heart and are directly correlated with the severity of heart failure. These biomarkers are especially helpful in emergency settings to rule in or out heart failure as a cause of acute symptoms.

Functional Classification Of Heart Failure

Another important tool in clinical practice is the New York Heart Association (NYHA) functional classification, which grades heart failure based on the impact of symptoms on daily life. The classification includes four classes: Class I indicates no limitation of physical activity and no symptoms; Class II involves slight limitation, where comfort is maintained at rest but symptoms appear during heavy exertion. Class III is marked by noticeable limitations during mild physical activity, and Class IV represents the most severe stage, where symptoms occur even at rest or in a lying position, significantly impairing quality of life.