My understanding, which may well be inaccurate, was that the diver in question had been revascularized and had either a valve repair or replacement. The time elapsed since the surgery is unknown, as is whether he had had any evaluation of the success of the revascularization.
I can't think of anything about the surgery (either one) that would predispose a diver to DCS. However, vein grafts do fail (rare, but it happens) and valves leak . . . it's not entirely far-fetched to imagine the diver developing chest pain or shortness of breath underwater and truncating his deco. Until we have some better information about the nature of the surgery, the time elapsed since it was done, and whether or not the diver had any evaluation (stress test) of the success of his revascularization, I don't think we can say very much at all.
Since he was awake and talking when EMS got to the site (at least from the report I read) one would think he would have told the emergency crew what happened.