Hello. I presume you mean Left Ventricular Ejection Fraction of 20%? I have had an implant for the last four and a half years (CRT-D) and have a low Ejection Fraction of 10%. My Cardiologist started me on Ivabradine two years ago as I met the criteria of being in Sinus Rhythm and having a resting heart rate above 80 bpm.
The effect on me has been to slow my heart rate to 60 bpm at rest. Whilst my Ejection Fraction has not changed my lungs / breathing is much easier and I can now sleep laying flat once again.
All the best to to you.
I am sorry to hear of your father's problems. You would need to talk to his doctor since he knows your fathers medical history and list of medications and tests done to find out the answer. New technology always comes our way, but it may not be for everyone. That is why I say discuss it with his doctor. Best wishes.