Sinus Tachycardia Depressions-PLEASE REPLY?

I was recently taken to the emergency room with tightness in my chest, tachycardia, palpatations, dizzy and sweaty palms. I was kept over night and admitted in the cardiac unit ONLY to wait and see if I had a possible heart attack. I had 3 EKG's. 2 were prior to taking the nitroglicern tablet in the hospital and were positive which showed mild depression. The 3rd one was negative (this was after 3 nitro-pills and morphine). I was sent home because I didnt have a "heart attack" BUT they have me doing a holter test and stress echo in a few days. Can you have a positive EKG and be fine...... I am not sure what to make out of all of this. I am a healthy 26 year old mother of 2. Any info would be great!

Also cardiac disease is VERY high in my family. There is a strong genetic dispotion of 50% of family members having mitro-valve prolapse

You can have very abnormal ECG's and still have a normal heart. Last week I admitted a female in her 70's with a "high risk" ECG and vague complaints. She had a cardiac catheterization and an echocardiogram both of which were essentially normal (age appropriate). If the two initial ECG's occurred when your heart rate was going very fast then the abnormalities may be rate related. It is not uncommon in tachycardia to see ST depressions. It is hard to tell initially if they are rate related or due to ischemia (area of the heart not getting enough oxygen).

The stress echo will be the deciding test to determine if you have any ischemic areas in your heart (increased risk for heart attack). The holter will help determine the presence of arrythmia (not related to ischemia).

You are a very low risk for having had a heart attack or for having ischemic heart disease. Your risk for having ischemic heart disease is likely in the 10% range