New HCM diagnosis. Worst symptom is mucus buildup. Is this normal?

Interesting. I too have mucus in my throat but I never related it to my HCM in any way.

Cardiomyopathy can lead to a cough and mucus buildup in the throat due to fluid backing up in the lungs and airways, written in a way that’s medically accurate and easy to follow.

Why Cardiomyopathy Causes Mucus in the Lungs:

Cardiomyopathy — whether HCM, DCM, or restrictive — can weaken or stiffen the heart. When the left ventricle cannot pump or fill effectively, blood backs up into the lungs.

This creates two processes:

1. Pulmonary Congestion (Fluid Backup).

When pressure rises in the pulmonary veins:

Fluid leaks from blood vessels into the air sacs.

Fluid mixes with surfactant.

This creates frothy or white “mucus”.

Lungs become irritated → airway glands produce more mucus.

Even though patients think it’s “phlegm,” much of it is actually fluid from congestion, not infection.

This is classic in:

Acute heart failure.

Hypertrophic cardiomyopathy with high filling pressures.

Diastolic dysfunction.

Mitral regurgitation caused by SAM in HCM.

2. Bronchial Mucus Gland Stimulation:

When the lungs are congested, the airway lining senses irritation.

This triggers:

Cough.

Thickened sputum.

“Rattling” feeling.

Worse when lying flat (orthopnea).

Episodes at night (PND).

Congestion makes airway glands overproduce mucus, especially in the larger bronchi.

What the Mucus Usually Looks Like.

Patients often report:

Clear or white mucus (most common).

Foamy sputum (very characteristic of pulmonary edema).

Occasional pink tinge if capillaries are stressed.

This is very different from:

Yellow/green infection mucus.

Thick plugs from asthma/COPD.

Why It Happens Specifically in Hypertrophic Cardiomyopathy (HCM):

HCM can raise filling pressures because:

Thick stiff ventricle → doesn’t relax well.

Mitral valve SAM → causes regurgitation.

Outflow obstruction → increases pressure against which the LV pumps

Any of these can elevate pressure in the left atrium → pulmonary veins → lung tissue.

Even if ejection fraction is normal, diastolic pressure is often high in HCM, which is enough to cause fluid/mucus.

Symptoms Patients Often Notice:

Shortness of breath.

Cough with clear sputum.

Difficulty breathing when lying flat.

Waking up at night coughing.

Wheezing not caused by asthma.

Chest tightness from congestion.

What Helps Reduce the Mucus (Medically):

The goal is to lower lung pressure, not treat it like an infection.

Effective treatments include:

Diuretics (e.g., furosemide) → pulls fluid out.

Beta-blockers → reduce filling pressures in HCM.

Avoiding excess salt.

Treating any mitral regurgitation/SAM.

Lowering blood pressure.

Optimizing HCM medications (metoprolol, verapamil, etc.).

Treatments NOT very helpful:

Antibiotics (unless infection).

Mucus-thinning meds alone (don’t fix the cause).

Cough syrups (just mask symptoms).

Main Cause of HCM:

1. Genetic Mutations (Most common — ~60–70% of cases).

HCM is usually caused by mutations in the genes that build the heart’s sarcomere, the contractile unit of heart muscle.

The most commonly affected genes include:

MYH7 (β-myosin heavy chain).

MYBPC3 (myosin-binding protein C).

TNNT2, TNNI3, TPM1, ACTC1, etc.

These mutations cause the heart muscle—especially the interventricular septum—to thicken abnormally.

Genetic HCM is inherited in an autosomal dominant pattern.

Meaning: a single copy of the mutated gene can cause the condition.

Less Common Causes:

These are NOT the “main” causes but can produce an HCM-like appearance (“phenocopies”):

2. Metabolic or storage diseases.

Fabry disease.

Amyloidosis (AL or ATTR).

Glycogen storage diseases like Pompe.

3. Mitochondrial disorders.

4. Noonan syndrome and related RASopathies.

5. Chronic high blood pressure or aortic stenosis.

These cause hypertrophy, but not true HCM (different mechanism).

Key Point:

True HCM = a genetic sarcomere disease.
This is the main cause unless proven otherwise.

Alcohol is harmful for people with (HCM), as it can also cause mucus buildup in the lungs.