A 78-year-old lady with long-standing hypertension on amlodipine was brought into hospital after seemingly 'passing-out' at home earlier in the day. This happened suddenly and without warning. She endorsed palpitations a few minutes prior to fainting. These palpitations have apparently been troubling her for months now and she's waiting to be seen by a cardiologist. In the ED, she's conscious and oriented x 3. BP was 110/64 mmHg, She had a rapid pulse rate of 178/min. She's diaphoretic but her cardiovascular examination was otherwise unremarkable. A 12-lead ECG was obtained and shown as below
Her laboratory investigations (sent from triage) were all within normal limits. c-Tn-T was 13 ng/L, serum K+ was 4.3 mmol/L.
Part (1) of this case
 what does the ECG show? what is the diagnosis/differential diagnosis?
 how would you manage the patient at this stage?