This 83-year-old woman has been brought to the emergency department 1 1/2 hours after onset of rapid palpitation associated with dyspnea and weakness. She had experienced 2 similar episodes during the past year, which were treated in another hospital:

• Atrial tachycardia with variable AV conduction
• Atrial rate 180/min. Ventricular rate 71/min  
• Left ventricular hypertrophy with repolarization abnormality

In view of the severe symptoms and evidence of congestive heart failure DC cardioversion was carried out: 

• Sinus rhythm, 68/min.  
• Minimal voltage criteria for left ventricular hypertrophy