Write SQL query to solve given problem: Among the patients that died, what is the condition of the oldest patient?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T1.DESCRIPTION FROM conditions AS T1 INNER JOIN patients AS T2 ON T1.PATIENT = T2.patient WHERE T2.deathdate IS NOT NULL ORDER BY strftime('%Y', T2.deathdate) - strftime('%Y', T2.birthdate) DESC LIMIT 1