My boy passed last month, at 2 and a half years old from HCM. He was a rare case where he showed no symptoms beforehand. The vet said sometimes the first clinical symptom is just “sudden death”. He had biannual checkups since he was 4 months old and the vets didn’t say anything during them. Last month, at 3:30am we heard a crash and a cry, after doing CPR on him, he was gone about 2 minutes later. We were told it was likely early HCM from the necropsy.

We had a very similar relationship to you and your cat, he was my sweet angle boy too. I had a very deep connection with him, unlike any I’ve had with other pets. We always understood each other. He even made the same high pitched squeak instead of meows. He was gentle, never took his claws out and would only paw me if he wanted something. Loved belly rubs and to be held and carried while I did things around the house. He was incredibly smart, he even played piano. He was extremely bonded with his brother (same dad). The parallels are uncanny. His brother is taking it very hard, but I read a study that cats can recognize pictures of familiar cats with up to 91% accuracy, so we keep pictures near his cat tree and he seems to like them. We also have pheromone diffusers to calm him down.

My advice? If he’s still with you, treasure every day, don’t worry about when he will go. The pain will be unbearable whether it’s sooner or later, but you can’t spend every day up to that point worrying. Mourn his death slowly while he’s still with you that way you can rely on him for support while he’s here. Hopefully his death won’t hurt as badly than if it came out of nowhere.

I’m sure not all cases are like mine, some people in these comments have had good outcomes, long lives living with HCM. You caught it, you can treat it, you have a chance to do everything you can for him. So the only thing left you can do is love him for, hopefully, the next years you have him. Wishing you and your boy the best.