The purpose of the sudy is to conduct a small study to gather the preliminary data for future lage scale clinical studies that will be designed test the potential beneficial effect of over-the counter study anti-oxidant drug called N-acetylcysteine (NAC) in patients with a heart muscle condition called Hypertrophic Cardiomyopathy (HCM). The present study is a pilot feasibility study, the investigators want to find out whether the investigators can recruit and retain patients with HCM in the study and whether these patients can tolerate this drug and can stay on one year. Likewise, the investigators want to find out any potential side effects that this drug might have and estimate whether ii has any beneficial effects.