An 82-year-old woman is brought to the Emergency Dept. from a nursing home because of weakness and dyspnea on mild exertion. She is been on a beta-blocker for moderate hypertension:

• Atrial tachycardia with 2:1 AV conduction; ventricular rate 100/min
• Minor voltage criteria for left ventricular hypertrophy (R1 + S3  = 25 mm  RaVL = 13 mm)
• Nonspecific ST abnormality, consider digitalis effect

Comment: The diagnosis of the computerized ECG system was “sinus tachycardia” (the non-conducted “P  on T” wave was missed). There were signs of congestive heart failure. The patient was admitted for further investigation and treatment. The beta-blocker was withheld.  

2 days later the patient complains of palpitation and dyspnea:

• Atrial tachycardia with 4:3 AV block, atrial rate 192/min, ventricular rate 142/min
• Non-specific ST and T abnormality