Yes and no - the faster you can get them to the hospital, the better the chance. But complete occlusion of one of many arteries or veins will lead to sudden death, and each minute that passes means death of the heart muscle. Heart muscle death means less likelihood of being able to restart the heart. Most commonly found in inferior MIs, whereby the blood pressure will plummet.

Truth is, there's still a lot about the heart we don't know, even in the areas of preventive medicine. It's possible a preliminary screening for cholesterol and high blood pressure would've caught it. It's also possible for his cholesterol and blood pressure and other markers to be normal.