I too wore a month long monitor, and had a couple of days of what was referred to as "poor recordings". Unfortunately, I also had a couple of events that were garbled to a point of being unreadable. In my case, I had either improperly place the electrode, or the electrode was not getting good conduction with my skin. In other words the "artifacts" were not being generated by my heart, but I guess could be called static on the recording. I also made sure that if I had an event, I paused or sat still hoping to insure a good recording.
The question I have is:
Did the artifact occur during times that you were experiencing palpitations and if so, might it have masked some events that they needed to look at more closely.
My monitors were really sensitive to movement, just walking or changing positions would affect my strip. If I wasn't sitting perfectly still, I would get strange stuff showing up on it.
But, the pads made my skin rot off and I was bleeding and oozing (still have scars 3.5 months later) and probably didn't have good contact the whole while.
As I understand your post your test didn't produce usable results, so it seems another try in in order.
If another test run is to be made be sure you have the proper management tools/training. It is critically important that the sensors (pickups) be placed properly. I know that when wearing a long term (couple of weeks or thereabouts) monitor I had to install the sensors each day and the monitor was read out often so if the reports looked "strange" I'd get a call asking me to check out my installation.