How do I add an "IF EXISTS" component to a WMI query of an MSMQ queue?

I have a WMI query of an MSMQ queue that works fine as long as there are messages in the queue:

Select MessagesInQueue From Win32_PerfRawData_msmq_MSMQQueue where Name="os:servername\\private$\\queuename")

But when there are no messages in the queue, it gets torn down and that queue name no longer exists.  When that happens I would like to return a 0, but the following returns an "Invalid Query" error:

IF EXISTS (Select * from Win32_PerfRawData_msmq_MSMQQueue where Name="os:servername\\private$\\queuename")

THEN (Select MessagesInQueue From Win32_PerfRawData_msmq_MSMQQueue where Name="os:servername\\private$\\queuename") ELSE 0

Any help?