instruction: how many patients whose primary disease is atrial septal defect\mitral valve replacement;repair atrial-septal defect/sda and year of death is less than or equal to 2126?
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.dod_year <= "2126.0"