instruction: how many patients admitted in emergency underwent percutaneous transluminal coronary angioplasty (ptca)?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN procedures ON demographic.hadm_id = procedures.hadm_id WHERE demographic.admission_type = "EMERGENCY" AND procedures.long_title = "Percutaneous transluminal coronary angioplasty [PTCA]"