From which point is door-to-balloon time measured in STEMI patients undergoing PCI?

• A. From first medical contact to balloon inflation
• B. From hospital arrival to balloon inflation
• C. From symptom onset to balloon inflation
• D. From ECG interpretation to balloon inflation

Answer: (A)

Door-to-balloon time measures how quickly the healthcare system can deliver definitive reperfusion after care has begun within the patient’s care pathway. It is defined as the interval from first medical contact to balloon inflation during PCI. This focuses on system performance—from the moment EMS or hospital staff first engages with the patient to the moment the blocked artery is opened.

This is why the other options don’t fit. From hospital arrival to balloon inflation misses prehospital contact and transport steps that occur before arrival. From symptom onset to balloon inflation includes patient delay in seeking care, which isn’t the aim of this metric. From ECG interpretation to balloon inflation ignores the many steps that happen after initial interpretation, such as activation of the cath lab and prep time.