West Ham, who looked the stronger side after levelling and hit the crossbar through Michail Antonio, have 31 points from 30 games, four ahead of the relegation places.
Arsenal had won all five of their London derbies away from home this season without conceding a goal and had lost only two of the previous 29 league games against West Ham.
“Very disappointing. The way we started was superb again, we were in total control, then we lost purpose,” Arteta said.
“We gave them hope, conceded a terrible penalty, then credit to them. We got on the rollercoaster where everything is going, corners and throw-ins, and we never got away from that.”
Arsenal remain in a position that they could have hardly imagined back in August, but with City steaming up behind them after collecting 25 points from the last 27 on offer, the odds are shifting towards Pep Guardiola’s treble chasers.
