Cardiac amyloidosis is a "stiff heart" disease caused by abnormal proteins depositing in the heart muscle, making it thick and rigid rather than weak in the way HFrEF is. It's increasingly recognized as an under-diagnosed cause of heart failure, particularly in older adults, and modern imaging has made diagnosis dramatically easier than it used to be.
What Is Cardiac Amyloidosis?
This is infiltration of the heart muscle by misfolded amyloid protein deposits — normal proteins that have folded incorrectly, clump together, and deposit in tissues throughout the body, including the heart. When enough amyloid builds up in the heart wall, it causes progressive stiffening, distinct from the muscle weakening seen in HFrEF. Amyloid deposits aren't limited to the heart either — depending on the type, they can also accumulate in nerves, the gut, and other organs, which is part of why some of the earliest clues (like carpal tunnel syndrome) show up outside the heart entirely.
What's Happening in Your Heart
Unlike HFrEF, where the muscle weakens, amyloidosis makes the heart muscle thick and stiff, impairing its ability to relax and fill with blood between beats — a "restrictive" pattern. The end result (heart failure symptoms) can look similar to other forms of heart failure, but the mechanism is fundamentally different, which is exactly why it needs a different diagnostic and treatment approach. Over time, the amyloid deposits can also disrupt the heart's electrical conduction system, contributing to arrhythmias and, in some cases, requiring a pacemaker independent of any heart failure treatment.
Types & Causes
- ATTR (transthyretin) amyloidosis — has two forms: wild-type (age-related, more common in older men, not inherited) and hereditary (genetic, can run in families — relevant for Family Screening & Genetics)
- AL (light chain) amyloidosis — related to an abnormal plasma cell/bone marrow process, generally more urgent to diagnose and treat given its different, faster disease course
Common Symptoms
Heart failure symptoms (shortness of breath, swelling, fatigue) are the usual presentation, but several features help distinguish cardiac amyloidosis from other heart failure phenotypes, including HFpEF (heart failure with preserved ejection fraction — in plain terms, a heart that pumps a normal percentage of blood but doesn't relax and fill well) from causes like hypertension:
- Low blood pressure that doesn't fit the picture — many patients with thickened heart walls "should" have high blood pressure from years of hypertension, but amyloidosis often causes unexplained low or dropping blood pressure instead, sometimes with lightheadedness on standing (orthostatic hypotension), since the stiff heart can't increase its output to compensate
- A heart that looks thick but doesn't act strong — despite thickened walls on echo, the pumping strength (ejection fraction) is often only mildly reduced or even normal, which can be misleading; more specialized measurements like strain imaging often reveal reduced function that a standard ejection fraction misses
- Low EKG voltage despite a thick-walled heart on echo — an important mismatch: hypertensive or hypertrophic hearts usually show high voltage on EKG, but amyloid-infiltrated muscle often shows normal or low voltage despite looking thick on imaging
- Carpal tunnel syndrome, especially bilateral, often appearing years before heart symptoms — one of the most useful early clues, particularly when it shows up in both wrists in an older man
- Spontaneous biceps tendon rupture or lumbar spinal stenosis — amyloid deposits in tendons and spinal ligaments can cause these problems years before a cardiac diagnosis is made
- Unexplained or difficult-to-control atrial fibrillation, sometimes with poor response to standard rate- or rhythm-control strategies
- Autonomic and GI symptoms — early fullness, alternating constipation and diarrhea, and unintentional weight loss, more common with hereditary ATTR
- Easy bruising, especially around the eyes ("raccoon eyes"), and an enlarged tongue (macroglossia) — specific clues for AL amyloidosis, not typically seen in ATTR
Red Flags: When to Suspect Amyloidosis Instead of "Typical" Heart Failure
Your care team is more likely to consider amyloidosis testing when several of these appear together, rather than any single one alone:
- A thickened heart wall on echocardiogram without a clear reason (no significant history of high blood pressure or valve disease to explain it)
- Heart failure symptoms plus a history of bilateral carpal tunnel surgery
- Low or falling blood pressure in a patient who previously needed blood pressure medication, or who can no longer tolerate it
- A mismatch between a "thick" appearance on echo and "low voltage" on EKG
- Heart failure with preserved ejection fraction that isn't responding as expected to standard treatment
- Unexplained peripheral neuropathy, especially alongside heart failure symptoms
- A family history of unexplained heart failure, neuropathy, or early death from "heart failure" in relatives (hereditary ATTR)
- Periorbital bruising or an enlarged tongue (specific to AL amyloidosis)
If several of these apply to you, it's reasonable to ask your doctor directly whether amyloidosis has been considered.
How It's Diagnosed
An echocardiogram often raises the initial suspicion (thickened walls); cardiac MRI adds detail; a PYP scan is a major advance that can diagnose ATTR amyloidosis without a heart biopsy in many cases; blood and urine tests distinguish AL from ATTR — a crucial step, since AL requires urgent hematology involvement; a biopsy is sometimes needed when other testing isn't conclusive. (See Cardiac Testing & Imaging and Lab Tests & Diagnostics.)
Main Treatment Options
Treatment depends heavily on the type — ATTR versus AL — since they require completely different approaches. (See Cardiac Amyloidosis Medications for a full breakdown of specific drugs, how they work, and what to expect.)
- ATTR amyloidosis is treated with TTR stabilizer medications (like tafamidis) that bind to the transthyretin protein and prevent it from misfolding and depositing further — these have been shown to slow disease progression and reduce hospitalizations. Newer TTR "gene-silencing" therapies, originally developed for ATTR-related nerve damage, are also increasingly used or studied for the heart
- AL amyloidosis is a hematologic disease at its core, and is treated by hematology/oncology, typically with chemotherapy-type regimens that target the abnormal plasma cells producing the toxic light chains — sometimes including a stem cell transplant in eligible patients. Because AL amyloidosis can progress quickly, treatment is usually started urgently
- Standard heart failure medications need to be individualized here. Many of the usual Heart Failure Medications: The Four Pillars used in HFrEF are often poorly tolerated in amyloidosis, because the heart's stiffness leaves little room to further lower blood pressure or heart rate — beta-blockers and blood pressure medications in particular can worsen already-low blood pressure and fatigue
- Digoxin is generally avoided or used with extra caution, since it can bind to amyloid fibrils in a way that increases the risk of dangerous heart rhythm problems, even at doses that would be safe in other patients (see Digoxin)
- Diuretics remain a mainstay for fluid symptoms in both types, and are usually well tolerated
- Anticoagulation is often considered even without a formal atrial fibrillation diagnosis in some amyloidosis patients, since the amyloid-infiltrated atria don't contract effectively even when the heart rhythm looks normal, raising clot risk (see Anticoagulants)
- Pacemakers are sometimes needed if amyloid deposits disrupt the heart's electrical conduction system, independent of any heart failure treatment
Lifestyle Changes That Help
General heart failure principles — fluid and sodium awareness — apply, along with avoiding certain medications that can worsen this specific condition. Some standard heart failure medications aren't well tolerated in amyloidosis, which is exactly why individualized guidance matters so much here.
Living With It
Outlook has improved significantly with earlier diagnosis and new ATTR-specific treatments. Hereditary ATTR raises family screening considerations worth discussing with your care team.
When to Call Your Doctor vs. Go to the ER
Follows similar heart failure warning signs — see Heart Failure with Reduced Ejection Fraction.
Common Questions
Is this the same as regular heart failure?
Related in symptoms, but a different underlying mechanism requiring different treatment — it's important not to assume standard heart failure treatment alone is enough.
Why did it take so long to diagnose?
Amyloidosis was historically under-recognized and required a biopsy to confirm; the PYP scan has made non-invasive diagnosis much more accessible in recent years.
Should my family be tested?
Only relevant for the hereditary ATTR form — your doctor can help determine which type you have and whether this applies to you.
What's the connection to carpal tunnel syndrome?
Amyloid deposits in the wrist can cause carpal tunnel syndrome years before heart symptoms appear — a bilateral carpal tunnel diagnosis, especially in an older man, is increasingly recognized as worth a conversation about amyloidosis screening.
Why can't I take the usual heart failure medications?
Because amyloidosis causes a stiff, restrictive heart with a fixed, limited pumping volume, medications that lower blood pressure or heart rate — normally the backbone of heart failure treatment — often cause more harm than good here; your team will tailor your regimen specifically for amyloidosis rather than using the standard heart failure medication list.