Can excessive caffeine lead to heart attacks thru fast pulse?

Not likely.: Heart attack occurs when there is a mismatch between amount of blood needed by heart muscle and amount that can be supplied by heart blood vessels. Technically yes, you can speed heart rate up enough to outstrip oxygen supply, but a normal stomach and thirst will probably limit caffeine intake first. With more potent vaso and cardio active meds or a damaged heart, it is entirely possible.