Hello. Thank you for your question. If this was a paroxysmal episode of atrial flutter, then there is only a slight chance that missing of a single dose of metoprolol causes it. This episode warrants treatment aiming converting this arrhythmia to sinus rhythm. The efforts in doing that should be undertaken in a healthcare facility where cardiac monitoring is readily available. This consists in compensating the possible electrolyte disturbances (mostly potassium levels), giving digitalis derivatives in intravenous route to slow down the heart rate with a chance of self-converting, or administering pharmacological therapy (amiodarone, propafenone) or electric shock (if hemodinamically unstable). After converting into sinus rhythm, proper therapy to maintain this rhythm should be instituted. I hope I was helpful. Take care.