Typical angina (chest discomfort or heaviness) was present for a median of 120 minutes in 25% of the 274 patients with witnessed arrest and in 33% with a symptom duration of less than 1 hour.There's no better way to precipitate a malignant heart rhythm disturbance that to deprive the heart oxygen, and angina is the classic symptom of this oxygen shortage. Symptoms can include chest "heaviness," or "pressure", a choking sensation, jaw discomfort, arm or back discomfort, including a sensation of a band-like grip around the chest - especially with exertion. Shortness of breath with exertion and even burping with exertion can be seen.
So why didn't these people summon help? Perhaps ignorance played a role.
More likely, though, it was denial.
PS: If this happens to you or a loved one, please call for help.... immediately.