"The ablation was successfully performed at Northwestern Hospital in Chicago on Monday morning and Brad returned to Arizona [on Wednesday]," the team said in a statement.
Wieck, 28, was acquired last season from the San Diego Padres, compiling a 0.600 WHIP in 14 games with the Cubs. The cardiac ablation should prevent a recurrence of atrial flutter.
"Brad will rest and rehab for the next week and be evaluated further to establish a timeline for resumption of pitching activities towards the end of the next week," the Cubs said.
Wieck is expected to be one of the lefties out of the bullpen this year. He has a career ERA of 4.97 in 49 games split between San Diego and Chicago.