Okay, your complaint and inquiry is very common among persons with anxiety. Understand that supraventricular extrasystoles simply means above the ventricles. In other words, extra atrial contractions. Realize that these particular events are not originated by the heart at all, but rather external to the heart by the vagus nerve. They are the equivalent of experiencing a muscle twitch in an eyelid. It is the result of a wayward nerve impulse that produces activity or contraction of the surrounding muscle and in the case of benign palpitations, the heart muscle is involved.

Because benign palpitations do not originate from the heart, they do not constitute any type of cardiac arrhythmia. Subsequently, benign palpitations can never transform into anything else other that as they now appear, no more than a leopard can become a lion. They are distinctly different in origin.

Witnessing a bank robbery or exposure to any event that is perceived to bring one within close proximity to fear of their life can sometimes produce a condition known as Post Traumatic Stress Disorder. It is common among certain combat soldiers, to a lesser extent among average citizens who encounter an extraordinary experience. It's important to understand that the problem exists at the level of persistence in the threat regardless of its distance in time and place.

It is a persistent state of alert which arises from the perception that danger remains close and unpredictable, causing constant vigilance to emerge. Somatic, or physical, features typically accompany PTSD and patients begin complaining of both physical and cognitive disparities from what they formerly recognized as normal.

The opportunity for witnessing a bank robbery in the manner described by you will virtually never happen again within your lifetime due to the statistics associated with such events. It's also critical to establish the perception of the encounter based strictly upon what did happen, rather than what could have occurred. Believing your life to be in danger is a matter of perspective, but must be regulated by known facts. In other words, people cannot really gauge to what extent they are exposed to danger because they don't actually have control over the environment in which the instance occurred. Therefore, they can come to believe that any range of outcomes could have arisen, most often the absolute worst. It is this perceived closeness that causes the experience to rival with walking the edge of a high cliff on unsteady ground, with the potential to slip and fall to a certain death at any given moment.

There are professionals within your region with expertise in dealing with  PTSD and I recommend that you consider seeking out and speaking with one in order to establish a firm direction for overcoming your difficulty with anxiety rather than merely dealing with it.

You're going to be just fine. There is nothing physically wrong with your heart and the palpitation events will not shorten your life by even as much as a second in time. They cannot transform into anything other than what they truly represent. You're in no danger whatsoever.

Best regards,

Rutheford Rane, MD (ret.)