Panic attacks lead to cardiopulmonary changes, which are changes that involve the heart and the lungs. Those are increases heartbeats, hyperventilation, chest pain, or even the perception of having difficulty breathing.
In addition, during a panic attack, there is also an increase in sympathetic tone, which is the branch of the autonomic system that contributes to arousal. Increased blood flow, high vigilance, muscle readiness, etc…are all examples of the effects of sympathetic activation.
All those changes can lead to an increase in anxiety, as well as heart problems such as hypertension, tachychardia, and myocardial ischemia (i.e., low blood flow to the heart).
It is important to keep in mind that those problems could potentially affect individuals who already have heart problems or who are elderly. If you are young and otherwise healthy, you are unlikely to develop such complications.