Known vs unknown?

Yes. And it's the naturalistic fallacy. Being natural doesn't mean safe and being unnatural doesn't mean dangerous.

I'm no expert in statistics but it came down to a 2+ percentage difference between groups. As well, although the groups were categorized from a starting point of no cardiovascular problems, the starting age is significant. Everyone 65 or older has increased risk of cardiovascular issues. I am no fan of aspartame, but, out of 60k women, the group who changed only represented under 10% of the total group and the difference was 8.5% of the women in more than two sodas a day vs. 7.2% in the group who consumed next to none. am I missing something here?

A few years ago I obtained a report about how aspartame was approved for human consumption. I have avoided it ever since. Aspartame is very bad stuff. I'll consume sucralose on occassion - but not aspartame.

I read it that the effect of the drinks did not become significant until the usage was at the 2 drinks per day level, and at that level it the incidence of heart attack was up from about 7% to about 8.5%. that looks more like a 20% increase to me. Perhaps the increase is more pronounced "when researchers adjusted for other cardiovascular risk factors and co-morbidities ?"
I agree with you, it isn't clear how they arrive at the numeric conclusions that are stated in the synopsis of the study.