The underlying cause for the heart wall to become thick and stiff can be related to high blood pressure, and other causes. Sometimes there can be reversed remodeling by treating high blood pressure if that is in part the cause. An overworked heart pumping against high resistance of narrow vessels causes the left ventricle wall and wall separating left and right side chambers (septum). Also, there can be thickening in other parts of the heart muscle, such as the bottom of the heart called the apex, right ventricle, or throughout the entire left ventricle.
Also, the wall thickening can happen as one ages, and slightly thickened my not be of any concern. Heart valve stenosis (narrowing of opening) if mild should not be of any concern...also part of aging process and the cause my be some calcification of leaflets and'or valve opening.
Surgery would not be an option nor appropriate as your post doesn't indicate a serious problem. If you have sympoms such as shortness of breath, fatigue, chest pain, etc., then repair or replacement of the heart valve would be a consideration. Proper management of blood pressure can help prevent any progression of enlarged heart and possibly reverse.
Thanks for sharing, and if you have any further questions this forum has very experienced and knowledgeable members that can help. Take care.