I'm Shirley, 61 year old female, suffers from this confusing problem. I have been on Zantac,Prevacid, Nexium and Aciflex. I still get this problem. I always get mine in bed, mostly after 12 midnight. Fluttering in my stomach, then the heart starts racing. Scares the heck out of me! I have been monitored and they found nothing. I will be getting a Stress Test next week. (3/2010 ) I start feeling strange on the left side just under the ribcage, it starts off with a rapid beating, pusling sensation, which then causes my pulse to go into overdrive. I feel it starts from the stomach. What worries me, will it eventually lead to a heart attack, since it causes my heart to start racing? It seems to start in the stomach, I do have heartburn problems. (Shirley)