Issajenko broke the world 50 m record indoors with a 6.06 clocking in Ottawa in 1987. She won a silver medal in 1987 World Indoor Championships in a tight finish with Nelli Cooman, both women were timed in 7.08, but after a photo finish the judges gave the Championship to Cooman, who looked to have crossed the line with her shoulder first. In the summer of 1987, she again broke the national record for 100 m with a time of 10.97 and finished fifth at the World Championships. Between 1979–1987, she was ranked inside the world's top ten in the 100 metres six times, and in the 200 metres three times.