One logical therapy to correct the defects arising from AF is return the abnormal heartbeats back to the normal rhythm. This can be done with electrical shock therapy (cardioversion) or by drugs called antiarrhythmic agents. Often, they are used together. While its stands to reason that using these techniques to restore rhythm to normal would be beneficial, clinical trials show that leaving patients in AF and thinning the blood to prevent blood clots is equally efficacious to trying to restore normal beating (sinus rhythm). The common explanations for this are that AF returns rapidly despite antiarrhythmic drugs and that antiarrhythmic drugs can make worse abnormal heart beats, a phenomenon known as proarrhythmia.