I've been to a cardiologist last week, mainly for routine checkup, but also because I felt somewhat tired and exhausted, not just lately but basically for my whole life, and I wanted to see whether it has anything to do with my heart. I'm 24 years old, male, 178cm, 70kg.
The echo showed that, while my heart is structurally perfectly fine, not the least bit enlarged, and no other anomalies, I do have a rather low left ventricular ejection fraction of 39%. Therefore my heart also beats pretty fast most of the time. That's it, though, everything else is perfectly normal.
The doctor didn't quite know what to make of it, said I'll have to do some more tests. His best shot was some sort of dilated cardiomyopathy, but to me that seems unlikely since there is absolutely no enlargement, and I'm 24 yrs old with no other health issues. I also don't have any specific symptoms, just a decreased stroke volume. Also, I felt tired and exhausted pretty much for my entire life, and I've always been rather sensitive to cold, and had very cold feet, so my guess is that my heart has always been like that.
My question is this: could such a "weak heart" simply derive from insufficient activity? For my entire life I've basically never done sports, I sit at my computer for literally the entire day, and I only go out to get food, if even that. Lately (2 months ago) I started running and going to the gym regularly, and that made me feel much stronger overall, but I still tend to be somewhat weak and exhausted.
Is it possible that a 39% LVEF, with no further anomalies, simply derives from a lifelong extremely sedentary lifestyle, or does that seem very unlikely? Do I have reason to believe that if I become an extremely vigorous exerciser my EF could improve to 60-70% or more after a year or two, or are such changes absolutely inconceivable? Note that I do not suffer from exercise intolerance, I can easily go running for an hour or more (while keeping a heart rate of 180-190 bpm), with no negative symptoms or anything. I just don't run very fast when I do.
Please consider that I'm not looking for a yes/no answer based on gut feelings, or some sort of reassurement, but information with scientific references that explicitly refer to this pattern of markedly decreased left ventricular EF / stroke volume in the absence of any structural change or further problems.