Collapsing from an anxiety attack may have happened, but until other things are considered and ruled out, it's a supposition. Plus, that was a diagnosis given to him by another physician. I NEVER trust the diagnosis of other physicians when I am confronted with a new patient. It's not that I don't respect them, but everyone makes mistakes and it's too easy to pass along a diagnosis that isn't correct. In this instance, what if he was having ‘panic attacks’ that happened to be secondary to a neuroendocrine secretory tumor that wasn't considered? What if he was having intermittent arrhythmias and was experiencing this as shortness of breath and lightheadedness that made him panicky?
You may have never heard of Dr. Gilbert Mudge, but he was a relatively famous cardiologist from Boston (Harvard Brigham and Women's Hospital). He wrote a textbook on EKGs that many, many medical students, residents, and fellows read as a part of their training. He's the doctor who told Reggie Lewis (a phenomenal basketball player with the Boston Celtics), that he could play basketball. This was after another hospital in Boston told him he shouldn't.
Lewis had passed out while playing a playoff game against the Charlotte Hornets. He was worked up initially at a different hospital in Boston, and found to have a hypertrophied (thickened) heart. Many high level athletes (e.g. competitive marathon runners) have thickened hearts because of the high work-load they endure. This is benign. However, people can also have pathological hypertrophy - which is associated with sudden death. It's sometimes hard to tell the difference. Now we have MRIs to help distinguish, but these were not readily available for the heart back then. The doctors at the first hospital weren't sure of the diagnosis, but erring on the side of safety they recommended he not play.
Lewis then sought a second opinion from Dr. Mudge. Mudge diagnosed him as having passed out from “neurocardiogenic syncope” (essentially fainting), and stated that he was confident Lewis could go back to playing professional basketball without limitations.
Not long thereafter Lewis dropped to the floor while shooting baskets at a college gym, and was pronounced dead at a hospital 2.5 hours later.
The point is that serious stuff happens, and every doc must take every patient seriously, even if their story sounds bogus. Prove it's bogus, but always err on the side of safety.
Because of my anxiety I know about things like WPW, LQTS, Brugada Syndrome, CPVT, and any other pure electrophysiological heart condition. As you know a simple EKG is often not enough to diagnosis such conditions. A holter or event monitor is a low cost option that can offer peace of mind at the very least.