Clinical question of the week: "Arrhythmia" patient with palpitations, dyspnoea, and dark stools

A 75-year-old male with a prior history of hypertension, diabetes and treatment for “arrhythmia” presented to the emergency department complaining of palpitations and dyspnea on exertion over the last two days. The patient also reported dark stools over the last two days. No other symptoms were reported. Current medications included atenolol 50 mg qD, warfarin 5 mg qD, metformin 850 mg BiD.   The patient did not remember his last INR result, but reported no blood tests over the last two months. On examination the heart rate was 140, irregular, BP was 90/70, respiratory rate 22, SatO2: 94%. The patient was pale, lungs were clear, and no other abnormalities were noted.   The EKG is below:  
Source: Doc2Doc BMJ Cardiology - Category: Cardiology Authors: Source Type: forums