In both cases, an irregular, premature electrical impulse is generated, and the ensuing contraction of the heart is sometimes perceived by the patient. They can also occur following a heart attack, and tend to reflect the degree of ventricular dysfunction and possibly the extent of untreated coronary artery disease. Finally, the incidence of premature beats increases with age and is associated with male sex. It sounds like you're undergoing a thorough evaluation for these symptoms. If the holter shows that you're experiencing episodes of atrial fibrillation, which is a more serious atrial arrhythmia, then your doctor can advise you on medical therapy for this condition that should decrease its incidence.
Some common medications are beta-blockers.
Other causes of palpitations can be detected by the holter and possibly by electrophysiologic testing using a catheter that is placed into the heart through the veins in the groin. This catheter-based technique, if indicated by the Holter results, can not only diagnose, but sometimes treat and cure these arrhythmias. As I mentioned above, this is a benign condition. Saying it's not harmful doesn't make it go away, but if in fact this is the problem, you need to understand that it's not dangerous. I recommend you discuss the findings of the Holter and Echocardiogram with your doctor in order to arrive at the appropriate plan of action.