A 79-year-old man was referred to the Emergency Department by his family physician. During the past 12 hours he had been complaining  of palpitation, weakness and dyspnea. He had been well treated for hypertension. Prior to the onset of palpitation he had been normally active and apparently well:

• Atrial flutter with 2:1 AV conduction
• Frequent premature ventricular complexes
• Ventricular rate 130/min  

The patient was treated with digoxin and a beta-blocker drug. His symptoms improved. This ECG was recorded 8 hours after ECG 1:

• Atrial flutter with variable AV conduction
• Ventricular rate 86/min
• Non-specific ST and T abnormality