Your grandfather, Thomas E. Wixtead died of a heart condition in December 1917, likely due to the stress of coordinating telegraph communications in the immediate aftermath of the Halifax Explosion. This accidental munitions detonation in Halifax, Nova Scotia was the largest human-made explosion prior to the invention of nuclear weapons. Thomas E. Wixtead was 54 years old. He left behind his wife and four children.
Your grandfather, Thomas E. Wixtead, was likely a related casualty of of the Halifax Explosion. He probably had a per-existing heart condition that became fatal due to intense stress.
Click on the image to see a larger view.