Father Had Two Small Heart Attacks. He Did Not Seek

Father had two small heart attacks. He did not seek medical attention. He later went to the hospital couple weeks later feeling terrible. The doctors did a procedure and gave him medication. At a later date they gave him a pacemaker. His heart function is only 20%. My father is in otherwise good health. Good cholesterol levels and weight. What is your estimate of his life expectancy. He is 75 years old and still very mobile.