Yes, I believe your understanding is lacking. Ambulances are dispatched for other medical emergencies as well. Compared to many other parts of Australia and even the world, the response time statistics claimed are very good.

Sadly, A heart attack can be fatal even with immediate medical intervention at a hospital. A defibrillator can only correct certain kinds of abnormal heart electrical activity.

In my experience as soon as the dispatcher understands it's a medical problem, has confirmed the address and that the patient is not breathing, they will begin talking the caller through performing CPR.

I suppose if I was concerned about it, the burden would be on me to move somewhere closer to the hospital or wherever the ambulance stages between calls. Unfortunqtely, there's always a chance no ambulance is available or that an accident has blocked the road.

How soon do you believe assistance should arrive?

For reference in Los Angeles, a notoriously traffic filled metropolitan area, the average response time for a life threatening ambulance call is 6 minutes and 14 seconds and 98.8% in under 15 minutes