instruction: count the number of patients whose primary disease is atrial septal defect\mitral valve replacement;repair atrial-septal defect/sda and admission year is less than 2164?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic WHERE demographic.diagnosis = "ATRIAL SEPTAL DEFECT\MITRAL VALVE REPLACEMENT;REPAIR ATRIAL-SEPTAL DEFECT/SDA" AND demographic.admityear < "2164"