Database: thrombosis_prediction
Question: For the examinations done after 1997/1/1, how many of them have the result of an inactivated partial prothrom bin time?
SQL: SELECT COUNT(T1.ID) FROM Patient AS T1 INNER JOIN Laboratory AS T2 ON T1.ID = T2.ID WHERE T2.Date > '1997-01-01' AND T2.APTT >= 45