We have just added the heartbeat monitor to our hotspot guard.
You can customize the heartbeat threshold in your account settings.
Whenever the difference between the current blockchain height and the last heartbeat (=POC activity) is greater than this threshold you will receive an email notification.
The default value is 480 which is roughly 8 hours.
Within the next days we will also enable the hotspot ping check for everyone and integrate it into the hotspot guard as well