Whether nutrient deficiencies or other metabolic imbalance is the cause is not clear or it may be a response to oxidative stress, however levels of the trace nutrients magnesium, selenium, zinc, and vitamin D3 were found to be low and the level of calcium elevated in myocardium, a type of muscle tissue in the heart. 
Karl T. Weber,1,* William B. Weglicki,2 and Robert U. Simpson3 Macro- and micronutrient dyshomeostasis in the adverse structural remodelling of myocardium, Cardiovasc Res. 2009 Feb 15; 81(3): 500–508.
Disclaimer: Opinions are my own and the information is provided for educational purposes within the guidelines of fair use. While I am a Registered Dietitian this information is not intended to provide individual health guidance. Please see a health professional for individual health care purposes.