import win32com.client as win32ComClient

wd = os.getcwd()

try:
    idea = win32ComClient.Dispatch(dispatch="Idea.IdeaClient")
    db = idea.OpenDatabase(os.path.join(wd, 'myfile.IMD'))
    task = db.TableManagement()
    field = db.TableDef().NewField()
    field.Name = "oldname"
    field.Description = "description"
    field.Type = WI_CHAR_FIELD
    field.Equation = ""
    field.Length = 1
    task.ReplaceField("newname", field)
    task.PerformTask
    task = Nothing
    db = Nothing
    field = Nothing
    idea = None
finally:
    idea = None