Try CAA they have really good travel insurance and you don't need to be a member

@A MyCOPDTeam Member I should have said be really thorough ( rather then honest), make sure u include everything.
Some policies will include pre existing conditions like cardiac but only if "stable"
So if you've had a change in medication, even a decrease because you are actually doing better they can choose not to cover if something happens.they seem to consider any change unstable.
Marketplace did a good program on this. You can probably stream it from CBC.
Their contracts are pages long.

Have you tried the Canadian Snowbird Association? https://www.snowbirds.org/medipac-travel-insurance
Perhaps they could provide some assistance?

You must get additional insurance and read policy very carefully, many will not cover existing conditions, or won't cover if you've had any treatment changes, even less meds in specific periods before travel.
They will sell it to u but u may not be covered.
And font even consider trying to get anything past them.
I know a woman, went to Arrizona, ended up in hospital $350,000.00 bill, she been to a walk in a few weeks before travelling for a stomach flu. Not related to her hospitalization but they refused to cover her as she hadn't reported it.
So read carefully and be scrupulously honest.

If you have additional insurance besides what you get as a Canadian citizen, I would start with them to see how or if your current insurance could be used in the US. I know there are Canadian companies that offer additional medical insurance and that's where I'd start. I know that for Americans traveling in much of the world, including Europe, the UK, Australia and Canada, medical services are made available very reasonably; in some cases at no cost at all. Unfortunately, I don't think the US is as advanced in our medical care payment methods.