Life Expectancy for Cats with HCM
By Dr. Kevin Toman, DVM · Medically reviewed November 1, 2026 · 40+ years in clinical practice · 300+ cats with HCM treated
Short answer: Many cats with mild HCM live for years, and some live a normal lifespan. Life expectancy depends mostly on the stage. In a study of over 1,000 cats with HCM but no symptoms, about 7 in 10 never had heart failure or a blood clot during the study. Once a cat has heart failure or a clot, average survival drops to about 1 to 2 years.
Your vet just said "HCM." Here's what that really means.
HCM (hypertrophic cardiomyopathy) means the wall of your cat's main pumping chamber has grown too thick. A thick wall gets stiff. A stiff heart has trouble filling with blood.
HCM is the most common heart disease in cats. About 1 in 7 cats has it. In cats over 9 years old, it's closer to 1 in 3.
Here's the good news: a diagnosis is not a countdown clock. What matters most is your cat's stage, and whether problems develop.
Life expectancy by stage
Vets use a staging system from the ACVIM (American College of Veterinary Internal Medicine). Think of it as a map of where your cat is on the road.
| Stage | What it means | What to expect |
|---|---|---|
| A | At risk (breed or family history), heart looks normal | No reduced lifespan from HCM yet. Screen regularly. |
| B1 | Thick heart wall, no symptoms, low near-term risk | Many cats stay here for years. Some never get worse. |
| B2 | Thick heart wall, no symptoms, enlarged left atrium or other risk signs | Higher risk of heart failure or a clot. Needs a closer plan. |
| C | Has had heart failure or a blood clot | More guarded. Many cats still get good months to years with treatment. |
| D | Heart failure that no longer responds well to treatment | Focus on comfort and quality of life. |
What the biggest study found
The REVEAL study followed 1,730 cats in 21 countries. It is the best long-term data we have. It included 1,008 cats with HCM but no symptoms at the start.
| Time after diagnosis | Heart failure | Blood clot (ATE) | Death from heart disease |
|---|---|---|---|
| 1 year | 7.0% | 3.5% | 6.7% |
| 5 years | 19.9% | 9.7% | 22.8% |
| 10 years | 23.9% | 11.3% | 28.3% |
What this means in plain words:
- Most cats did well for a long time. In the first year, fewer than 1 in 10 had a heart problem.
- Risk adds up over the years. That's why regular checkups matter even when your cat seems fine.
- The big turning point is the first crisis. Cats that developed heart failure or a clot lived about 1.3 years on average after that event.
The lesson: the goal is to catch changes before a crisis.
From Dr. Kevin's 400+ cats with HCM:
The earlier we catch HCM and begin treatment with Felycin-CA1, the longer your cat will live. It's that simple.
The other factors that drive survival in HCM kitties are secondary diseases like kidney disease and hypertension, so grab a urinalysis and remind your vet to check your cat's blood pressure.
Oh, and one other thing. Let your cat play. It's their quality of life that we are after.
6 things that change your cat's outlook
- Size of the left atrium. The left atrium is the heart's upper holding chamber. When it stretches, blood moves slowly and clots can form. This is the single most important thing to ask about.
- How thick the heart wall is. Thicker walls usually mean a stiffer heart.
- Heart failure. This is when fluid builds up in or around the lungs. It changes the outlook a lot.
- Blood clots. A clot that blocks blood to the back legs (a "saddle thrombus") is an emergency.
- Other diseases. Kidney disease, an overactive thyroid and high blood pressure all make HCM harder to manage.
- How closely your cat is watched. Regular heart ultrasounds and home breathing checks catch problems early.
Can a cat with HCM live a normal lifespan?
Yes, some can. In the REVEAL study, about 1 in 10 cats with HCM lived 9 to 15 years after diagnosis.
But HCM is hard to predict. Two cats with the same ultrasound can follow very different paths. A cat that eats, plays and breathes normally can still have a changing heart. That's why checkups matter even when your cat looks healthy.
What you can do starting today
- Know your cat's stage. Ask your vet: "Is it B1 or B2? How big is the left atrium?"
- Count sleeping breaths. Count breaths for 30 seconds while your cat sleeps, then double it. Write it down. Call your vet if it stays higher than your cat's normal, or goes over the limit your vet gives you.
- Book repeat heart ultrasounds. Your vet will set the timing. Higher-risk cats need them more often.
- Check blood pressure and thyroid. Both can make the heart wall thicker.
- Know the emergency signs. Open-mouth breathing, struggling to breathe, sudden back-leg weakness or crying in pain means go to an emergency vet now.
Is there treatment that targets the thickening itself?
For decades, HCM drugs only managed the problems HCM causes, like clots and fluid. That changed in 2025.
Felycin-CA1 (a cat-specific, delayed-release form of sirolimus, also called rapamycin) was conditionally approved by the US FDA in March 2025. It is the first drug approved for HCM in cats. It is for cats whose heart wall is thickening but who don't have symptoms yet.
It does not cure HCM, and it does not replace checkups. Read our full guide to sirolimus and Felycin for cats →
Is your cat a candidate? Take the 3-minute Felycin candidate check → [DR. KEVIN: add link]
Outside the US?
We ship Felycin routinely to the US, UK, and Canada. You start by sending your vet's prescription, or by enrolling your cat in our Cat Longevity Protocol. You can purchase Felycin from us and get guaranteed delivery, although it sometimes takes a few days.
If you live in the EU, Taiwan, Hong Kong, or China you can purchase Felycin from us. You start by enrolling your cat in our Cat Longevity Protocol. You provide the shipping, and we cannot guarantee delivery but we can absolutely send it your way.
Frequently asked questions
Does HCM always shorten a cat's life?
No. Many cats with mild, stable HCM live for years. Some live a normal lifespan.
How long can a cat live with Stage B1 HCM?
Many cats stay in Stage B1 for years. Regular ultrasounds show whether the heart is changing.
Is Stage B2 HCM a death sentence?
No. B2 means higher risk, not a set outcome. A good plan can lower the chance of a crisis.
How long do cats live after heart failure?
In the REVEAL study, cats lived about 1.3 years on average after heart failure or a clot. Some lived much longer. Response to treatment varies a lot.
What is the most urgent warning sign?
Open-mouth breathing, struggling to breathe, collapse, or sudden back-leg weakness or paralysis. Go to an emergency vet right away.
Your next step
Got an echo report and not sure what it means? Dr. Kevin can help you.
Or start with our free guide: HCM University.
References
- Fox PR, et al. The REVEAL Study. J Vet Intern Med. 2018;32(3):930–943.
- Luis Fuentes V, et al. ACVIM consensus statement on cardiomyopathies in cats. J Vet Intern Med. 2020;34(3):1062–1077.
- Kaplan JL, et al. RAPACAT trial. J Am Vet Med Assoc. 2023;261(11):1628–1637.
- US FDA. FDA conditionally approves drug for management of ventricular hypertrophy in cats. March 2025.
This article is for education only. It does not replace an exam, diagnosis or treatment plan from your own veterinarian. Prices and regulations change; confirm locally.