Depends on cause. Syncope can be due to a simple faint (like having blood drawn) or it can be due to serious heart disease with dangerous arrhythmias. The causes are legion. Some don't involve the heart at all like low blood sugar or epilepsy. You should discuss your syncope with someone who knows your full medical history to see if additional testing is necessary.
No. Probably not -- but you can certainly hurt yourself as a result of syncope so I would strongly recommend that you address the matter if you have syncope.