I absolutely agree with Jerry - lifestyle changes; even in the smallest amount can help. If I had not done that a few years ago my heart may not have been strong enough to withstand the ordeal it's been through the past year.
walking is free - you can do it inside or outside - pick up cans of veggies and lift "weights"; since you have the internet - find chair exercises on the web for free - there are free exercise videos that you can do and some are actually "fun"
you say you have "lots of pvc's" what is your defition of lots? have you had a holter monitor or other monitor to tell you how many exactly? If not, ask for one and a stress test, echo etc just to be sure
anyone at any age CAN have unhealthy plaque buildup - google the icd support groups or heart disease groups - some of these people are young and have problems. If you are worried about plaque the worst thing you can do for yourself is be inactive - not just exercise, but inactivity can lead to alot of problems including depression
If you have a game system; find one of the games that get you moving; I did that after heart surgery and that's one reason I think I didn't develop alot of afteraffects. Cut back on soda's, caffeine, sugars; alcohol and whatever else you may think is a trigger for you.
I am one of those who had "constant persistant pvc's" over 54,000 day in day out....these monsters wouldn't go away no matter what changes I made. I had to have an ablation and pacemaker/icd implanted because were malignant and caused my heart to stop. Luckily, because I've had an "ok" lifestyle and good genetics; my cardiac cath showed no plaque, buildup or problems.
Do something for yourself while you're 23 and don't end up later in life regretting not taking care of yourself now. That's the same thing I tell my oldest children who are your age and see what I've been through.
Well, here in the USA, a doctor/cardiologist would give me a quizzical "eye" to say the least if I walked in at your age and suggested I needed an, I would call it, angiogram. I think it very unlikely you have any blocked arteries, and if there is any concern in that area the doctor would likely do a stress test, much simpler and not invasive.
Sound like you need to take you BB, and I encourage you to adopt a healthy diet, minimum sugar (especially refined sugar) is a good start.