A patient with angina experiences chest pain radiating to the neck during dental treatment. Nitroglycerin is administered three times (3 rounds) but symptoms do not resolve. What is the MOST appropriate next step?

Correct answer: C. Activate emergency medical services (call 911) — the presentation has changed to probable myocardial infarction

• A. Oxygen is appropriate but must be combined with activating EMS — monitoring alone is insufficient for a probable MI.
• B. A fourth nitroglycerin dose is not protocol — after 3 doses without relief, the presumptive diagnosis is MI and EMS must be activated.
• C. Correct. The protocol for angina is: 1) Assess ABCs, 2) Administer 100% oxygen, 3) Give nitroglycerin up to 3 times (every 5 minutes). If symptoms persist after 3 doses of nitroglycerin, the diagnosis changes to probable MYOCARDIAL INFARCTION (MI). The immediate action is to call 911, then administer aspirin (325mg chewed), and prepare for CPR if needed.
• D. Aspirin should be given for suspected MI, but only after activating EMS — discharging the patient would be dangerous.