Is Mild Left Ventricular Diastolic Dysfunction Concerning?

Hello and good day to you! I had an echocardiogram done and was diagnosed in October, 2010 with mild left ventricular diastolic dysfunction. I was told not to worry about it. But I am worried because my heart is impaired! My cardiologist told me that it is reversible in me because I am slender, and have no other risk factors that contributed to this. He said I should just exercise more. He said my ventricle has stiffened from normal aging. I am 58 years old. Is he correct? I'm afraid of this progressing to heart failure. Can it? If so, what steps should I take to stop the progression, and is exercise all that is needed? I feel like I am being patronized and it's very upsetting to me. I am a 58 year old female. I have SVT, Pac's, and Pvc's frequently for many years, along with chest pains quite often. But, I am told my heart is structurally sound. How can it be structurally sound when I have all these problems coming from my heart, along with the most recent diagnosis of LVDD? I would appreciate any response from you. Thankyou so very much for your time! Sincerely, Joan