What is the key sign of a heart attack?

Chest pain or discomfort is recognized as the key sign of a heart attack because it often indicates that the heart muscle is not receiving enough oxygen and nutrients due to blocked blood flow. This discomfort can manifest as pressure, squeezing, fullness, or pain in the center or left side of the chest. It may last for more than a few minutes or go away and return. Recognizing this symptom is crucial for prompt treatment, as timely medical intervention can significantly improve survival rates and outcomes.

While other symptoms like headache, nausea, and fainting can occur during a heart attack, they are not as specific or prominent as chest pain or discomfort. For instance, headache may arise from various non-cardiac issues, nausea can be associated with many different conditions, and fainting may occur for numerous reasons not directly related to a heart attack. Thus, chest pain or discomfort stands out as the most critical and indicative sign of this medical emergency.