Seattle Sounders forward Clint Dempsey will sit out the rest of the 2016 season because of an irregular heartbeat, the MLS club announced on Tuesday.
Dempsey, 33, was initially sidelined by the symptoms last month but returned to light training on Sept. 14. Sounders general manager Garth Lagerwey said at the time that he was "cautiously optimistic" that the U.S. international would return by the end of the campaign, though he declined then to give any kind of timetable.
But Dempsey stopped training last week, leading to Tuesday's announcement.
"We simply haven't got to a point where we were comfortable that there was a realistic chance" of Dempsey returning this year, Lagerwey told reporters. "As we said in the first round of comments, we are not comfortable putting any kind of pressure on this.
"His return to play is not important relative to his health, both short- and long-term. We feel by ruling him out today it puts us in the best position to get him back, hopefully for the start of the 2017 season."
- Seattle Sounders FC (@SoundersFC) September 27, 2016
Lagerwey added that no further updates are likely to come until training camp next season, though he did shed a bit more light on the process Dempsey has gone through over the last month.
"Dempsey had been getting some tests over the course of a couple of months," he said. "We got some data that showed an irregularity. We then took him out and proceeded to begin this evaluation. That process is still underway.
"It was something that we had found over the course of him playing for us, and we had been tracking him and monitoring him over time and it popped up. It's something we have to take care of and we can't take any risks with something as serious as this.
"We started monitoring him, I don't know, two months ago. The monitoring then picked up some irregularities with the heartbeat and that's what we've been trying to address."
In the meantime, Seattle will have to carry on without Dempsey. The Sounders are currently in seventh place in the Western Conference, three points behind arch rivals the Portland Timbers for the sixth and final playoff spot with two games in hand.
"The mindset of the group is strong," interim head coach Brian Schmetzer told reporters. "Clint is a big factor, but they will persevere."
In addition, Dempsey will sit out the remaining four games that the United States national team has scheduled this year, including a pair of World Cup qualifiers against Mexico and Costa Rica in November.
Dempsey is in his fourth season in Seattle and recorded eight goals and two assists this year. All told, Dempsey has 37 goals and 23 assists in 82 regular-season and playoff appearances. He has also played for English sides Fulham and Tottenham Hotspur, as well as the New England Revolution of MLS.
Dempsey is the U.S. men's national team second all-time leading scorer, having scored 52 goals in 130 appearances.