A319
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Aircraft Equipment Problem Less Severe
Aircraft Equipment Problem Dissipated; Flight Crew Overcame Equipment Problem
Aircraft
First Officer was the Pilot Flying. Three minutes after level off at FL350; Engine 1 stall ECAM [was displayed] with loud banging from the #1 engine. Followed the Non-Normal methodology. Ran the ECAM action. With power on the #1 engine at idle we were unable to maintain altitude. Descended to FL240. Finished the QRH follow up procedure.  #1 engine showed all indications normal. Landed without further incident. Startle factor was in full effect. Took me good minute to wrap my head around the event. It was mechanical so I doubt [I could suggest] anything. Add it to a training event perhaps.
A319 First Officer reported descending to a lower altitude after experiencing #1 engine compressor stall at FL350.