Your father's heart is pumping about 38% of the blood filled in the left ventricle. When the contractility of the LV is normal there is a range of 50 to 70% referred to as ejection fraction (EF). If the heart walls have lost some of strength to pump normally, the cause is almost always due to heart muscle impairment.
Heart wall impairment can be due to a number of different causes that effect the heart muscle. It can be heart cell damage due to a heart attack, cell damage from toxic environment and/or ingestion (med, drugs, medication), high blood pressure, etc.
Whether your father can ioncrease the contractility of the heart depends on the underlying cause. You father may have an enlarged left ventricle and this condition can cause weaker than normal contractions. There could be a valve problem, structual abnormality, etc. About 7 years ago I had an enlarged left ventricle due to high blood pressure, and this condition decreased my EF to below 30%. The size of the heart returns to normal size after medication dilated vessels and with less burden the overworked heart return to normal size and EF went into the normal range.
If you have more information regarding the concomitant health issues that may be the underlying cause, there can be a better understanding of hearts viablility going forward. Thanks for sharing and if you have any further questions or comments you are welcome to respond.
Ken