How to save attached Appointment from ItemAttachment object in Exchange EWS ?

I`m able to do this with EmailMessage

Item message = Item.Bind(_service, new ItemId(item.Id.UniqueId.ToString()), new PropertySet(BasePropertySet.FirstClassProperties, ItemSchema.Attachments));
           foreach (Attachment attachment in message.Attachments)
           {
                var attItem = attachment as ItemAttachment;
                attItem.Load(new PropertySet(ItemSchema.Attachments));
                mimeContent = attItem.Item.MimeContent;
            }

But I`m wondering how I can do this with Appointment ?

Thank you for help!