Welcome to HCM. I have read your concern over and I understand why it doesn't make sense to you. However, this is a common occurence to have triglycerides elevated and there is a slightly different approach to getting them down.
In answer to your question, yes, we consider high triglycerides to be bad not only for the heart but your
pancreas as well. And to answer your other question about 275 being dangerous. It is in the high range and cardiologists/diabetologists would like to see it lower than 150, some settle for 200 depending on your risk profile.
You can do this by:
Limiting saturated fat( 7% of calories)
Exercising 250 minutes per week-walking, ellipticals,cardio best
Losing weight if overweight
Avoiding alcohol
Avoid sugar and fructose/desserts
Increase water soluble fibers (oats, legumes, skins of fresh fruits)
Omega-3 fatty acids are well-known in the literature to lower triglycerides along with several other beneficial effects.
I hope this answers your question and provides some guidance.Kathryn Shattler, MS,RDN