It would seem that a Holter Monitor may help, you'd have 24 hours worth of recorded rhythm. If it happens daily, that's a possibility.
I had an elusive fast beat, instant increase in rhythm, last for a few seconds to a few minutes, then go back to normal. We didn't catch it on the Holter, so I was provided with an event monitor. These may be worn for one week to a few weeks, and when an abnormal rhythm is noticed, the results are phoned in to an office (24 hours/day) that makes an analysis of the rhythm and would advise you what to do if there was a problem. The event monitor can be removed for showering, unlike the Holter, so having it for many days is no issue.
Mine, finally captured on the device, was phoned in. The call taker reviewed the rhythm, and in an almost bored voice, said "oh, you had a little PSVT". He didn't tell me to rush to the hospital or call an ambulance, so that was a relief.
In my case, no change in medication was warranted after I spoke with the doctor (the next day or so). Have you considered these monitoring options?