I have had and MRI and tilt tablet test to try and find out why I have had two syncope but no results. I do have a arrhythmia. Could you please help?

Follow cardiologist. Your arrhythmia need to be controlled.
Other tests. You may be a candidate for an implantable loop recorder. This is a little metal box as big as your little finger implanted under the skin in the chest area. It can record rhythm problems for up to several years, allowing your doctor to correlate your heart rhythm with any more syncopal spells.
Need more info. Syncope can be caused by many problems, some realtively "benign" and some serious. Of course, true syncope is scary adn can cause injury. If you have a dysrhythmia, that is a likely cause depending on what kind. Other causes of syncope can be determined by the evals, but also consider medications, seizures, and just straightforward faints (vasovagal syncope) - which can happen for many reasons.