Understanding Heart Failure: Types, Stages, Treatment, and the Role of Clinical Trials

Heart Failure Is Not What Most People Think

Heart failure does not mean the heart has stopped. It means the heart cannot pump enough blood to meet the body's demands. This distinction matters because heart failure is a chronic, progressive condition that affects over 6 million adults in the United States alone, and the number is rising as the population ages.

Understanding the types, stages, and treatment options is the first step toward managing it. For patients who have exhausted standard therapies, clinical trials offer access to investigational treatments that are not yet available to the general public.

Three Types of Heart Failure

Heart failure is classified by ejection fraction (EF), the percentage of blood the left ventricle pumps out with each contraction. A normal EF is 55-70%.

HFrEF (Heart Failure with Reduced Ejection Fraction)
EF below 40%. The heart muscle is weakened and cannot contract forcefully enough. This is the most studied form and has the most treatment options.

HFpEF (Heart Failure with Preserved Ejection Fraction)
EF 50% or above. The heart pumps normally but is too stiff to fill properly. This accounts for roughly half of all heart failure cases and has historically had fewer effective therapies, though that is changing with SGLT2 inhibitors.

HFmrEF (Heart Failure with Mildly Reduced Ejection Fraction)
EF 41-49%. A middle category where treatment decisions are guided by the dominant clinical picture. Many patients transition between categories over time.

The Four Stages

The ACC/AHA staging system describes heart failure as a continuum:

Stage A: At risk. No structural heart disease, no symptoms. Risk factors include hypertension, diabetes, obesity, coronary artery disease, family history of cardiomyopathy.

Stage B: Pre-heart failure. Structural heart disease (reduced EF, valve disease, LV hypertrophy) but no symptoms yet.

Stage C: Symptomatic heart failure. Structural disease with current or prior symptoms: shortness of breath, fatigue, fluid retention, exercise intolerance.

Stage D: Advanced heart failure. Marked symptoms at rest despite maximal medical therapy. These patients may require mechanical circulatory support, transplant, or palliative care.

Stages only move forward. A Stage C patient whose symptoms resolve with treatment is still Stage C, not Stage B.

Common Symptoms and Diagnosis

The hallmark symptoms are shortness of breath (especially lying flat or during exertion), persistent fatigue, swelling in the legs and ankles, rapid or irregular heartbeat, reduced ability to exercise, and persistent cough or wheezing.

Diagnosis involves a combination of physical examination, blood tests (BNP or NT-proBNP), echocardiography to measure ejection fraction and assess structure, ECG, and sometimes cardiac MRI or catheterization.

Modern Treatment: The Four-Pillar Approach

For HFrEF, guideline-directed medical therapy (GDMT) now centers on four drug classes initiated as early as possible:

1. SGLT2 Inhibitors (dapagliflozin, empagliflozin): Originally diabetes drugs, now proven to reduce heart failure hospitalizations and cardiovascular death regardless of diabetes status.

2. ARNI (sacubitril/valsartan): Replaces traditional ACE inhibitors or ARBs. Reduces mortality and hospitalization.

3. Beta-Blockers (carvedilol, metoprolol succinate, bisoprolol): Slow heart rate, reduce workload, improve survival.

4. MRAs (spironolactone, eplerenone): Block aldosterone, reduce fibrosis and fluid retention, improve survival.

Beyond medications, device therapies play a critical role. ICDs (implantable cardioverter-defibrillators) prevent sudden cardiac death. CRT (cardiac resynchronization therapy) improves pumping efficiency in patients with electrical conduction delays.

For Stage D patients, options include LVADs (left ventricular assist devices) as a bridge to transplant or destination therapy, and heart transplantation itself.

Why Clinical Trials Matter for Heart Failure

Despite significant advances, heart failure remains a leading cause of hospitalization in adults over 65. Five-year mortality exceeds 50% for many patients. Current therapies manage the condition but do not cure it.

Clinical trials are where the next generation of treatments is tested: gene therapies targeting cardiac fibrosis, novel device-based interventions for HFpEF, next-generation mechanical circulatory support, and precision medicine approaches that match therapies to individual patient profiles.

Participation in a clinical trial provides access to investigational therapies under close medical supervision, often with more frequent monitoring than standard care.

Amavita Research Services: Cardiovascular Clinical Research in Miami

Amavita Research Services is a cardiovascular clinical research site in Miami led by Dr. William O'Neill, one of the most experienced interventional cardiologists in the United States. The site is GCSA-certified and IAOCR-accredited, specializing in heart failure, TAVR, PAD, and atherectomy trials.

If you or someone you know is living with heart failure and interested in learning about clinical trial options, contact Amavita Research Services at www.amavitaresearch.com.