Metoprolol Tartrate:
The mean elimination half-life of metoprolol is 3 to 4 hours; in poor CYP2D6 metabolizers the half-life may be 7 to 9 hours.

Metroprolol Succinate:
Elimination is mainly by biotransformation in the liver, and the plasma half-life ranges from approximately 3 to 7 hours. 

This drug has a short half-life. Though not related, Xanax averages 11.2 hours, Klonopin 35 hours, and Valium 100 hours, once they have reached a steady state. I give this example to show how short the half-life of Metroprolol is.

I wouldn't do anything without your cardiologist's knowledge and hopefully approval, or approval of another doctor familiar with your health and conditions, like that which may happen to those seeking Emergency Room Treatment.

I'd think that within 48 hours, the Metroprolol would be out of your system, for all intents and purposes.

I'm taking 200 mg Metoprolol Succinate in the morning, 25 mg Metoprolol Tartrate mid-afternoon, and 150 mg Metoprolol Succinate at night. My cardiologist prescribed 200 mg Metoprolol Succinate in the morning and 200 mg Metoprolol Succinate in the evening, but my family doctor is aware how I'm taking it and did not object. Prior to my afib I was taking Acebutolol 200 mg three times a day, it's another Beta-Blocker, I no longer take that, but it seems I'm fairly tolerant of significant doses of, at different times of course, different Beta-Blockers.