VPCs In 12 Spayed Female Dog

Name: "Lily" (lets say since I prefer to remain anonymous on reddit)

Species: Dog

Age: 12

Sex: F (spayed)

Breed: Pit Bull (APBT or Staffy I think, with strong Boxer characteristics and some DNA tests say some Boxer content)

Body Weight: 55-60lbs. (BCS 5/9 at least check I believe)

History: Boxer type heart murmur since age 1-2 at least, not believed to be a problem in her life and cardiologist said minor, MCT at age 2, no recurrence, plenty of lumps/bumps/lipomas, FNAed frequently, bw less than a year ago which came back normal, in good health and romping and playing often. She has always had perhaps acid reflux that causes either hacking or reverse sneezing maybe once every couple days, and occasional vomiting.

Medications: 40mgs Fluoxetine SID, Omeprazole SID, Carprofen (for joints) 50mg BID. Heartworm and flea/tick px of course, but we may have given it up to a couple weeks late once or twice in the past year.

Clinical signs: None that we noticed expect possibly decreased appetite in the AM (though due to the reflux this isn't completely uncharacteristic.

Location: MI, USA

What is going on?

Our dogs got into a fight over food, which has never happened in the 4 years they have lived together, however, it may be the first time she left food in her bowl and he found it before we did. Taken to ER immediately for small laceration from fight. She was very stressed.

Vet noticed the murmur, as happens sometimes, but also an arrhythmia. ECG done resulting in about 10 VPCs over a 5 minute period. Vet described them as minor and unlikely to affect her, but might be pathologic. Cardio followup recommended and we will be scheduling of course.

I am very concerned however, as I know cardiomyopathy and tumors could be the cause (from speaking with vet and internet.) I know she is 12 (or about to turn 12), but she has been in excellent health otherwise, and of course she is my baby. I am very depressed about what this might mean, and wondering if anyone can help me understand before the cardio appt, which if I recall might take weeks to get in.

I'm hoping for some understanding of how likely certain causes are. I'm very concerned over the possibility of DCM. She has not been eating grain free, but boutique foods that I hoped were still safe. Can anyone shed any light on prognosis, or what, in their experience, would be the likelihood of different causes? If it neoplasia, will it get worse? If it's cardiomyopathy, are the meds to stop the spread? Any prognosis information would be wonderful. I'm taking this very hard, and honestly have become very depressed at the thought of what it could be. I have always been hyper-vigilant about her health, and hoped she would live to 15 or longer.

Thank you so much in advance!