Temporary pacemakers (TPM) are utilized in emergency situations when severe bradyarrhythmias secondary to acute myocardial infarction (AMI) and to non-AMI related cardiac disorders. Malposition of pacemaker lead is rare complication during pacemaker implantation. Here we reported a unique case found inadvertent malposition of temporary pacemaker lead passing through patent foramen ovale (PFO) into the left ventricle (LV) during emergent percutaneous coronary intervention for ST-elevation myocardial injury (STEMI).