They state, "The absence of significant changes in heart rate and blood pressure before and after exercise supports these supplements' short-term cardiovascular safety..." however they had already excluded the populations most likely to be affected. Any article about the study, therefore, should qualify that statement with a note that safety is not established for people with heart or thyroid issues or stimulant allergy,  or for women. Even if they did that, though, most people with cardiac or thyroid issues don't know it.