The Harder the Heart, the Harder It Breaks: A Case of Complete Atrioventricular Block Secondary to Tertiary Hyperparathyroidism.

The appearance of first-degree atrioventricular block and mitral annulus calcification in an end-stage renal failure patient with elevated parathyroid hormone levels should raise the suspicion of metastatic cardiac calcification. Measures should be taken to normalize the parathyroid hormone, calcium, and phosphorus levels to limit the progression of atrioventricular block. Exploration or removal of parathyroid glands should be considered if heart block worsens.