a 32-year-old previously healthy man presents to the ed with a 4-hour history of palpitations. he denies chest pain, shortness of breath, or history of similar palpitations. he does admit to heavy alcohol use in the past week, drinking 1 pint of vodka and a 24-pack of beer each day. in the ed, his vital signs are bp 135/75, hr 115, rr 14, and oxygen saturation 98% on room air. an irregularly irregular rhythm is heard on auscultation and an ecg shows irregularly irregular qrs complexes without p waves. what is the next step in management?