Coffee may protect people against irregular heartbeats

This study follow participants that will continue with coffee consumption or stop it. That means that is unclear if the stop consumption after being drinking coffee is the reason for the change in atrial fibrilation. And, there were important factors that were different between the two groups that are not addressed in the analysis, and it is unclear how much that affects the results. This study can be used to start bigger follow up studies with better controls and design to validate the effect of coffee.