Metastatic calcification of the cardiac conduction system with heart block: an under-reported entity in chronic renal failure patients

Systemic metastatic calcification is a common complication of chronic renal failure. Cardiac involvement is particularly ominous, especially when the cardiac conduction system is affected. Conduction defects, arrhythmias, and sudden death have all been reported with conduction system calcification; however, these are relatively under-reported or unrecognized causes of cardiac morbidity and mortality. We describe a 40-year-old man with Von Hippel-Lindau disease who had been maintained on hemodialysis for two years following bilateral nephrectomies for renal cell carcinoma. The patient presented with symptomatic complete heart block that had progressed from Mobitz type I atrioventricular block. Two months later, while being internally paced, the patient died unexpectedly after a complicated hospital admission. Postmortem revealed extensive vascular, myocardial, and conduction system calcification. Conduction system calcification may cause sudden death in chronic renal failure patients during hospital admission, or unexpectedly while the patient is in the community. Knowledge of this condition is necessary to detect it, as the conduction system is not routinely examined. A routine abbreviated conduction system examination is warranted for patients with systemic metastatic calcification, especially if they have sudden death or a known history of heart block.