There is no fixed time for how long it takes for electrical cardioversion to recur, and the degree of effectiveness is determined by the nature of the arrhythmia. Treatment after recurrence requires a physician.
The mechanism of cardiac electrical cardioversion is to use high-energy electric current in a short period of time through the chest wall or directly acting on the heart, so that all parts of the heart muscle are depolarized at the same time in an instant, and the sinus in the cardiac conduction system, which has the highest autoregulation, restores the role of its cardiac pacemaker to dominate the cardiac beat again, eliminating ectopic rhythms and restoring the sinus rhythm.
Some tachyarrhythmias may be effectively terminated by a single electrical resuscitation. However, some tachycardias may not respond to electrical resuscitation, or the resuscitation may be short-lived, e.g., reoccurring after 5 to 6 minutes. This may require multiple shocks or even defibrillation.