But you're lucky, relatively speaking. If you were shot in the heart, your blood pressure would quickly drop, but it would take 10 to 15 seconds to lose brain function. In that time you could draw your gun, utter last words, or spend some time thinking about your unfortunate situation.
Caffeine can cause indigestion, which in turn may lead to heart palpitations. However, arrhythmia (abnormal heart rhythm) can also cause palpitations, and this condition is more of a concern. Seek medical attention if your palpitations last longer than two or three minutes.
One symptom to look out for is that the pain from indigestion due to a heart attack may actually spread to the left shoulder and or arm. It may be associated with cold sweats, violent vomiting, feeling of the heart racing (palpitations), general weakness and shortness of breath.