What medical condition can coffee and the like exacerbate?

https://medical-dictionary.thefreedictionary.com/tachyarrhythmia

Thanks @Caravanfan
I just found as to why rapid heart beat could mean problem.
“A high heart rate can also mean the heart muscle is weakened by a virus or some other problem that forces it to beat more often to pump enough blood to the rest of the body.”

“Usually, though, a high heart beat is not due to heart disease, because a wide variety of noncardiac factors can speed the heart rate. These include fever, a low red blood cell count (anemia), an overactive thyroid, or overuse of caffeine or stimulants like some over-the-counter decongestants. The list goes on, and includes anxiety and poor physical conditioning.”
https://www.health.harvard.edu/heart-health/should-i-worry-about-my-fast-pulse