Anxiety of itself is never a direct "cause" of strokes or heart attacks but if you are predisposed to having a stroke due to already present health problems such as severe hypertension, it can be a contributing factor or trigger for these. I know this from much research I've read by PhD MDs and Psychiatrists over the past five years.
The anxiety "flight or flight" response temporarily elevates bodily functions; heart rate, BP, respiratory, sweating etc..., the same way exercise does, which can also be potentially dangerous for people with already existing health-risks.
Anxiety itself is a natural emotion and is designed to be triggered often if needed without physically harmful effects. Anxiety is not stress but a "bodily reaction to stress"; a pressure valve in a sense or the body's way of trying to shed off the stress (eliminating danger from stress).
Adrenaline/epinephrine that occurs naturally in the body, has a limited effect, or a cut off level of strength and is counteracted by noradrenaline/norepinephrine. It is metabolized by the body in such a way, that it cannot continue to escalate and cause death or severe health effects, in otherwise healthy people. If it could, people would be dropping dead from anxiety left and right every day because statistics state that up to 25% (1 in 4) people have an anxiety problem/disorder at some point in their lives and for a large percent of these people, it is chronic. If anxiety frequently caused severe health problems, then God or nature has made an error in giving us this mechanism.
My purpose in pointing this out, is to differentiate anxiety from "causing" and "contributing" to severe health problems. Anxiety among many other things, can contribute to all kinds of health problems but in most of these conditions, is not a direct cause.
One aspect of anxiety is "worry" however, since everyone on earth with very few exceptions, has worry, it has to be severe and chronic (ongoing) to be classified as an anxiety disorder. This type can contribute to a variety of health problems as well because chronic worry increases bodily functions, but more subtly.
While some people may believe confusing these terminologies is not that important, it really is because in some cases it results in wrong diagnosis, proposed causes for health problems, etc... It probably sounds like "semantics" or "playing with words" but it's really not and in my opinion people should know the difference.
Increased adrenaline over long periods of time, does contribute to serious health problems, such as hypertension and high cholesterol that can then directly cause heart problems and stroke, so these are the direct causes, while anxiety can be a contributor.
Anxiety doesn't cause these problems in all people, some don't develop hypertension or high cholesterol from prolonged anxiety, which are the things that almost always do cause serious health problems over time.
Just like everyone else, anxiety sufferers need to incorporate daily exercise into their routine and improved diet practices because this alone can offset any harmful effects from prolonged anxiety which can contribute to the hypertension and elevated cholesterol we have discussed above.
It is important in my opinion, for people with anxiety disorders, especially those who experience panic attacks, to know that the harmful effects of anxiety are almost never immediate unless as stated above, there is already a co-existing, serious health problem. By believing the anxiety is so very harmful in otherwise healthy individuals, it makes it very hard for these patients to learn not to fear any immediate effects from anxiety. Learning not fear anxiety symptoms is a major feature of Cognitive Behavioral Therapy (CBT) but an aspect patients will have little benefit from, if they are told the anxiety will directly cause them strokes, heart attacks or sudden death.

