The HR strap may work with other apps (which support Bluetooth 4.0) but it may connect differently than the smartPulse app. Please follow the instructions of the other app for installation and use. There are many compatible apps available on iTunes (runtastic, runkeeper…).
You must connect the HR strap separately to each app you use. You can’t connect in one app and have it recognized in others simultaneously. To use with another app, first close the smartPulse app, then restart your device before connecting to the different app.