A man with palpitations

A man in his 80s presented to the emergency department with recurrent episodes of chest tightness, shortness of breath, and palpitations, which had become worse over the previous week. He was a cigarette smoker and had a history of hypertension. On initial evaluation he had a heart rate of 84 beats/min and blood pressure of 110/70 mm Hg. His lower legs were oedematous. Laboratory test result for brain natriuretic peptide was 1869.20 ng/L (reference range <100 ng/L) and for troponin I was 0.0210 μg/L (reference range 0-0.0340 μg/L). Transthoracic echocardiography showed biatrial and biventricular dilations (left > right), left ventricular systolic dysfunction, trivial mitral regurgitation, mild pericardial effusion, and a left ventricular ejection fraction of 30%. A 12-lead electrocardiogram (ECG) was obtained on admission (fig 1). During hospital admission, the patient experienced palpitations, and electrocardiography was repeated (fig 2).