Asystole occurs when no electrical activity of the heart is seen. This may be a fatal arrhythmia when it occurs related to a severe underlying illness (septic shock, cardiogenic shock, post-PEA arrest). Emergent implementation of Advanced Cardiac Life Support (ACLS) is crucial in this situation.
Asystole can also be related to intrinsic conduction system disease. In this situation, the pause of electrical activity may be brief (few seconds) and result in syncope, however spontaneous recovery of sinus rhythm may occur. Treatment for this form of asystole is permanent pacemaker implantation.