Yоu hаve respоnded tо а 72-yeаr-old female patient with syncope and dizziness. ECG findings include:Rate- 52Rhythm- regularPR interval- less than .21 sQRS- less than .12ST- no up or down slopeT- No variantQT- less than .44 sU- slight elevationWhat is the most appropriate treatment at this time?