The terms cardiomyopathy and heart failure are often used interchangeably, causing confusion between two distinct medical conditions. While closely linked, they describe different aspects of a failing heart. Cardiomyopathy refers to a disease affecting the physical structure of the heart muscle, while heart failure is a clinical syndrome describing the functional outcome of the heart’s impaired ability to pump blood. Understanding the difference between the underlying disease and the resulting functional problem is key to grasping heart health.
Defining Heart Failure: A Functional Syndrome
Heart failure (HF) is a functional syndrome where the heart is unable to pump sufficient blood to meet the body’s metabolic demands, or can only do so by maintaining abnormally high filling pressures. This condition is not a specific disease diagnosis but a description of symptoms and signs resulting from structural or functional impairment. The inability to pump blood effectively leads to systemic issues like fluid congestion, manifesting as shortness of breath, fatigue, and swelling in the legs and ankles.
Clinically, heart failure is classified based on the left ventricular ejection fraction (LVEF), which is the percentage of blood pumped out of the main chamber with each beat.
Heart Failure with Reduced Ejection Fraction (HFrEF) is diagnosed when the LVEF is 40% or lower, indicating a problem with the heart’s squeezing action.
Heart Failure with Preserved Ejection Fraction (HFpEF) occurs when the LVEF remains 50% or higher, suggesting the problem is the heart muscle becoming stiff and failing to relax and fill properly.
A third category, HF with Mid-Range Ejection Fraction (HFmrEF), covers cases where the LVEF falls between 41% and 49%.
Understanding Cardiomyopathy: Disease of the Heart Muscle
Cardiomyopathy is defined as a primary disease of the myocardium, or heart muscle, causing it to become morphologically and functionally abnormal. This structural problem affects the muscle tissue itself, leading to changes in the heart’s shape and size. These structural changes directly impair the heart’s ability to pump or fill with blood, making it a disease rather than a functional syndrome.
The condition is broadly categorized into three structural types.
Dilated cardiomyopathy (DCM) is the most common form, characterized by the thinning and stretching of the heart chambers, which impairs the heart’s ability to contract forcefully.
Hypertrophic cardiomyopathy (HCM) involves an abnormal thickening of the heart muscle walls, which can obstruct blood flow and make the chambers smaller and stiffer.
Restrictive cardiomyopathy (RCM), the least common type, involves the heart muscle becoming stiff and rigid, preventing the ventricles from fully relaxing and filling with blood.
The Relationship: How Cardiomyopathy Leads to Heart Failure
The relationship between the two conditions is best understood as cause and effect: cardiomyopathy is a disease state that can progress into the functional syndrome of heart failure. The structural damage inherent in cardiomyopathy—stretching, thickening, or stiffening—ultimately compromises the heart’s mechanical efficiency. For instance, in DCM, the stretched muscle cannot generate enough force, leading directly to the reduced pumping function seen in HFrEF. Similarly, the stiffening in RCM prevents proper filling, which causes the high pressure and congestion defining HFpEF.
Not every case of heart failure is caused by cardiomyopathy; many other long-standing conditions can lead to the heart failing to pump effectively. Uncontrolled hypertension, for example, forces the heart to work against excessive pressure over time, leading to muscle strain and eventual failure. Coronary artery disease, which causes heart attacks and scarring, is another common cause that damages the muscle and leads to heart failure without being classified as a primary cardiomyopathy. Heart failure is the final common pathway—the clinical consequence—of numerous underlying cardiac problems.
Tailoring Treatment Based on the Underlying Condition
The distinction between cardiomyopathy and heart failure is reflected in the approach to treatment, which requires a dual focus. Management for heart failure concentrates on alleviating symptoms and preventing disease progression. This involves medications like diuretics to manage fluid congestion and beta-blockers or angiotensin receptor-neprilysin inhibitors (ARNIs) to improve pumping efficiency and reduce the heart’s workload.
Treatment of the underlying cardiomyopathy targets the specific cause or structural abnormality of the muscle itself. For example, a patient with a genetic form of HCM might receive specific medications to relax the muscle or have an implantable cardioverter-defibrillator (ICD) placed to mitigate the risk of sudden cardiac death. In cases of alcohol-induced DCM, the primary treatment involves complete abstinence from alcohol to potentially reverse the structural damage. This layered approach ensures that while functional symptoms are managed, efforts are also made to address the root cause.