Our Treatment
Diagnosis and Discussion
This patient experienced complete heart block due to a cardiac tumor from papillary thyroid carcinoma metastasis. Complete heart block is not an unprecedented symptom of metastatic disease, but to our knowledge this is the first reported case of heart block secondary to metastatic papillary thyroid cancer.1 In general, metastatic cardiac tumors, usually associated with cancers of the breast and lung, melanoma, and lymphoma, are more common than are primary cardiac tumors and are often asymptomatic and discovered mostly postmortem.2,3 The frequency of thyroid metastasis to the heart has been reported to be as low as 0% to 2%, and a review of the literature demonstrated only 13 total cases in the past 30 years.
Theoretical mechanisms for invasion into the heart include lymphatic spread, hematogenous dissemination, or direct right ventricular invasion from the thoracic duct. It has been suggested that the lower blood flow to the myocardium (240 mL/min) relative to bone (600 mL/min) or the brain (750 mL/min) is the reason for a lower likelihood of cardiac involvement in metastatic disease.3 Given the findings in this case, evidence of cardiac conduction abnormalities in the setting of papillary thyroid cancer should raise suspicion for cardiac metastatic disease.
Case Outcome
In this patient, a permanent pacemaker was implanted for high-grade atrioventricular block, with resolution of the palpitations. The pulmonary emboli were concomitantly treated with enoxaparin, and the patient was discharged to a rehabilitation facility. Her prognosis was extremely poor given that survival with cardiac metastasis from any type of cancer is limited to a few weeks to months.3 She was to be reevaluated for experimental chemotherapy after reconditioning. However, not long after discharge she was readmitted in respiratory failure and died.
Acknowledgments
We would like to thank Dr. Kevin Steel, Lt Col, USAF, MC, imaging cardiologist at the Brooke Army Medical Center for his time and effort in accessing and preparing the CT and MRI images for this article.
Author disclosures
The authors report no actual or potential conflicts of interest with regard to this article.
Disclaimer
The opinions expressed herein are those of the authors and do not necessarily reflect the official policy or position of Federal Practitioner, Frontline Medical Communications Inc., Brooke Army Medical Center, the U.S. Army Medical Department, the U.S. Army Office of the Surgeon General, the Department of the Army, Department of Defense, the U.S. Government, or any other of its agencies. This article may discuss unlabeled or investigational use of certain drugs. Please review complete prescribing information for specific drugs or drug combinations—including indications, contraindications, warnings, and adverse effects—before administering pharmacologic therapy to patients.