My thoughts are on a different branch of this concern, Jim, so I won't take much of your time. When my nephrologist suggested a strong beta blocker to treat my hypertension, I did some research and found a worry. Research into diastolic dysfunction (especially a project in which a Mayor cardiologist from Korea participated) popped into view with a warning that beta blockers were a threat to those with diastolic dysfunction. So I talked to my cardiologist about whether the beta blocker was a bad idea.

Not at all, he said. "You have a-fib which is, by definition, diastolic dysfunction, and we often use beta blockers in such cases." Turns out the risk from beta blockers occurs when the diastolic dysfunction is caused by something other than a-fib (giving me another lesson in reading medical research reports carefully).

So I agreed to the new medication (Carvedilol, which is a kidney-friendly beta blocker). You can see that I'm on the atrium branch of this tree, not the ventricle branch that is your focus. But one chamber succeeds the other, and the ventricular ejection fraction may be reduced when the atrium fails to fill and then deliver maximum blood (received from the lungs) into the ventricle for distribution to the body.

You're looking for substances to ameliorate diastolic dysfunction. I found a lot of hope in the research report you cited from the National Institutes of Health. The second paragraph of the introduction gave me strong encouragement to get 3 or 4 grams of omega-3 fats every day, because the NIH study finds them to be useful in cases of congestive heart failure, which is my main concern since my a-fib diagnosis two years ago.

Hope you find something in my experience to raise your hopes as well.
Martin