What should the therapist do if a patient reports chest pain during exercise and remains unchanged after 20 minutes of rest?

In cases where a patient reports chest pain during exercise that does not resolve after 20 minutes of rest, it is critical to prioritize the patient's safety and well-being. When chest pain is persistent, it can be a sign of a serious underlying condition, such as cardiac issues, which may require immediate medical attention.

Calling an ambulance ensures that the patient can receive prompt medical evaluation and intervention if necessary. Emergency services are equipped to assess the patient’s condition rapidly and can provide critical care en route to the hospital. This option reflects an understanding of the potential severity of the symptoms and the need for professional medical assessment.

While other responses, like allowing exercise resumption or reducing exercise intensity, may seem reasonable in a general context, they could pose serious risks in the presence of unexplained chest pain that hasn't resolved, as these actions fail to address the potential immediacy of a cardiac event. Encouraging a physician appointment also does not provide the urgent care required in this situation since it delays assessment and treatment. Hence, the decision to call an ambulance is the most appropriate and safe action to take in this scenario.