For someone age 42 the odds of having a heart attack are about 97 in 100,000. The odds of a cardiac event due to COVID vaccine are two orders of magnitude lower.
This is the post hoc fallacy and proportionality bias. Just because one event follows another doesn't mean they're connected. Further, humans are biased to think big and impactful outcomes must have big and impactful causes. [1]
It is simply far more likely that she independently had a vaccine and a heart attack. It sucks, to say the least, but it happens.
When you give billions of people the vaccine you'll get basically everything happening after someone gets a vaccine including a death by train derailment. It's simply far more likely they're not connected at all.
You saw one anecdotal report of a bad thing that happened to someone after they took a COVID vaccine, without any evidence they were connected. I'm sure more than once someone took a tylenol and got hit by a bus. That doesn't mean taking tylenol causes getting hit by a bus.
This is why anecdotes aren't a substitute for medical research.