Angiograms are considered an invasive procedure, but they are very safe. I've had about a dozen with no more complication that a big bruise. You will be sedated, and won't remember much, and it will be pretty much painless.
Sharp pains are generally not cardiac in nature, but it is always wise to check out any chest pains, especially if you have high risk factors like obesity, diabetes, or certainly if you smoke.
If I had an Ejection Fraction of 73%, I'd be celebrating.