At 9pm Thursday my heart went into overdrive. At the emergency room I was diagnosed with acute atrial fibrillation and was scheduled for electric cardioversion but the problem went away on its own (as it sometimes does) so I was discharged in late afternoon yesterday, after a 16 hours long hospitalisation with no food or drink (cardioversion requires anesthesia). A noninvasive echocardiogram detected no faults in my heart, and no reason for the attack was identified. I am told this is a good thing and means I have a very good prognosis (it is likely that the problem will never recur). I feel fine now.
The hospital visit was educational. I learned stuff about hospital procedures and some things about the equipment they use there, and met various people. I’m glad I had to make the call (if you have to go to the ER, it’s best if it’s for something nontrivial so they don’t feel you’re wasting their time but still something relatively dangerless).
A bit more detailed report in Finnish is available.