instruction: provide the number of patients who had total calcium lab test and are diagnosed with percutaneous transluminal coronary angioplasty status.
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id INNER JOIN lab ON demographic.hadm_id = lab.hadm_id WHERE diagnoses.short_title = "Status-post ptca" AND lab.label = "Calcium, Total"