Brady-tachycardia syndrome after radiotherapy for lung cancer - Assessment by computed tomography and carbon-11 methionine positron emission tomography

A 74-year-old male who had received radiotherapy (total 54 Gy) for right lung cancer 7 months earlier developed a symptomatic brady-tachycardia syndrome requiring the implantation of a permanent pacemaker. Chest CT showed a pulmonary tumor of 2-cm diameter in the right lower lobe with direct extension into the surrounding tissue, suggesting the possibility of cardiac invasion. Carbon-ii methionine positron emission tomography (PET) indicated the absence of visible invasion of the beast with lung cancer. The brady-tachycardia syndrome, therefore, was considered to be associated with sinus node injury due to radiation. Carbon-ii methionine PET metabolic imaging might play an important role in evaluating noninvasively the cause of the arrhythmia in this patient.