Variables in Advanced Alert Manager

I am trying to compose an alert email that shows the last time the node was polled in my local time (EST).

The following query works great to show the time 4 hours earlier than right now:

${SQL:Select DATEADD(hh,-4,GETDATE())}

However, that's not what I want. I need the last system uptime, which is found in the variable ${LastSystemUpTimePollUtc}. So I tried the following variations:

• ${SQL:Select DATEADD(hh,-4,${LastSystemUpTimePollUtc})}
• ${SQL:Select DATEADD(hh,-4,{LastSystemUpTimePollUtc})}
• ${SQL:Select DATEADD(hh,-4,LastSystemUpTimePollUtc)}
• ${SQL:Select DATEADD(hh,-4,LastSystemUpTimePollUtc())}

Respectively, I got the following result in the test email:

"

MACRO SQL ERROR - Incorrect syntax near '5'.

${SQL:Select DATEADD(hh,-4,{LastSystemUpTimePollUtc})}

MACRO SQL ERROR - Invalid column name 'LastSystemUpTimePollUtc'.

MACRO SQL ERROR - 'LastSystemUpTimePollUtc' is not a recognized built-in function name.

"

Does anyone have an idea?