Can palpitations resulting from stress and emotional anxiety result in sudden cardiac arrest? how do relaxants such as xanax (alprazolam) and lexaurin help?

Palpitations and stress: Xanax, (alprazolam) enhances release of GABA's in the brain, which has inhibitory activity on the brain's output of excitatory neurotransmitters, including norepinephrine, serotonin, acetyl choline and dopamine. Anxiety generates release of catecholamines on the conduction system of the heart, and on the myocytes. Which precipitates premature contractions, in presence of coronary disease may result in death