With the match locked at 4-4 in the final set, Edmund went down clutching his ankle and after being helped to his feet by Dimitrov, the British number two told a physio that he had heard "a crack".
Edmund completed the match and moved relatively freely on his heavily-taped ankle, but Dimitrov broke during his next service game to complete a 6-3 6-7 6-4 victory.
After six straight holds, Edmund created the first break points of the contest in the seventh game but after Dimitrov survived both times, the Bulgarian struck on his opponent's serve to seal the first set.
The second followed a similar pattern with Edmund competing with Dimitrov in the majority of the rallies, but Dimitrov squandered two break points at 4-3 up and was taken to a tie-break.
Edmund had been threatening to put together a series of point-winning shots and they came in the breaker as the 22-year-old produced several baseline winners to take it 7-3.
Both players continued to impress during the decider but Edmund's injury scare led to a lengthy break in play and both players had lost their rhythm when play resumed.
However, after Dimitrov held to lead 5-4, Edmund made a number of unforced errors and that allowed the top seed to eventually seal the win in two hours and 25 minutes.