Well i want to add to this discussion that i don't think 37 is dangerously low. I was never considered low until under 30 which os the point im told they normally consider being in Congested Heart Failure. When i first started having problems with mine i was at 5% and a pacemaker with difibulator installed. I went home on Amiordione and Cardivolol. I lived that way for over 3 years living a normal life until my pacemaker had to shock me back one time. But my point being is mine never got better than 40-45 untill my Heart transplant 2 years ago. So at least for me i was at 37 for years without any major issues. My pacemaker only had to shock me because of arrythmias not heart failure. Just my history with Low ef.