Good question. First, I would really say that no one should be going it alone with planning how to combat things related to heart disease. A doctor should always be your primary source of information. And a doctor that knows you and oversees your health. So, make sure you run everything by your doctor and come up with a mutually agreed upon plan. Niacin HAS been used to lower triglycerides and raise HDL (good) cholesterol. Improving these two aid in overall improvement in total cholesterol numbers. But niacin can have real draw backs too. You MUST talk to your doctor before starting a niacin supplement in my opinion. And if you are on a cholesterol lowering medication already, it may have no effect at all. It IS in a lot of multi vitamins and in food we eat, you are already getting some niacin. https://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/in-depth/niacin/art-20046208
Things to look out for when using are skin rashes, gi issues and possibly impact on developing type 2 diabetes. https://health.clevelandclinic.org/can-niacin-be-harmful-to-control-cholesterol/
So, it 'could' be beneficial but needs some doctor input to see if it is right for you.