Complete AV block following mediastinal radiation therapy: electrocardiographic and pathologic correlation and review of the world literature.

The clinical, features, serial electrocardiograms, and autopsy findings of a patient with symptomatic complete AV block, who had received mediastinal radiation therapy 8 1/2 years previously, are presented. The cardiac histopathology disclosed immense fibrosis of the conduction system and of the atria and ventricles. The enormous amount of fibrosis was similar in location and intensity to that observed in our previously reported patient (Cohen et al., Arch Intern Med 1981; 141:676-679) who had undergone mediastinal radiation. We conclude that the severe fibrosis was primarily due to radiation, rather than secondary to atherosclerotic coronary artery disease, which also has been described as a consequence of mediastinal radiotherapy. This patient's serial electrocardiograms disclosed evidence of complete block both in the AV nodal area and infra His system, which correlated well with the histopathology. The characteristic clinical features of patients with symptomatic complete AV block post mediastinal radiation therapy are presented, along with a review of the world literature.