Dr. Kristin MacDonald (at the Animal Care Center in Rohnert Park, California) gets a big "thumbs up" from me. She has a PHD on top of a specialty in cardiology and is well published in her research on HCM in Maine Coons. The Animal Care Center has top of the line equipment for x-rays and echos plus a well rounded staff of other veterinarians in various other specialties. Kristin's husband, Dr. Lavely, is also a veterinarian with a specialty in Neurology and sees our other cat, Hamlet, once a year for an examination related to his epilepsy.
Dr. MacDonald has a couple of small children and currently works Mondays through Wednesdays so you will need to call ahead for an appointment. We have been working with her for well over a year and go in routinely for echos, x-rays, blood tests, etc. My Maine Coon cat, Moe, would not be alive today if we had not made the move from our regular veterinarian to working with Kristin to try to stay on top of this progressive disease. Under her guidance, we were able to get Moe on a drug protocol that works well for him. Although his HCM is pretty severe, he is happy, perky, and has a high quality of life which makes all the minor ups and downs along the way worthwhile. Definitely find a good cardiologist and work with them. Most normal veterinarians just aren't up on the latest research and drug protocols necessary to keep on top of HCM. The cardiologists see many cats with varying degrees of severity and side complications come through their doors. Every cat is different but they know what works best based on their past cases. Dr. Kristin is highly flexible and will give you the straight scoop on your cat's prognosis plus fight like hell to slow the progression of the disease.
All the Best. Please feel free to contact me if you have any questions.
Mary and Moe