Ejection Fraction less than 25%-severe anemia

MY HUSBAND BEGAN EXPERIENCING SHORTNESS OF BREATH A FEW MONTHS AGO. hE HAD STRESS TEST, THEN WAS SCHEDULED FOR A CATH WITH POSSIBLE STENT. uPON RESULTS OF BLOOD DRAWS AT CATH LAB, DISCOVERED THAT HIS HEMOGLOBIN WAS 6.7, SO HE WAS TAKEN TO THE EMERGENCY ROOM. SUBSEQUENT FOUR TRANSFUSIONS RAISED HEMO TO 10.0, SO CATH WAS DONE AND FOUR STENTS WERE PLACED. Upon discharge from hospital yesterday, was told that EF was less than 25% and he now has a Life Vest. Could the anemia have caused the heart damage and if so, is there possibility of improvement of EF?