In "The Story of an Hour," how you tell someone what happened is almost more important than what actually happened. The biggest concern isn't whether someone lives or dies, it's how you tell a person with a weak heart bad news without killing her. In other words, communication or news can be lethal. Surprising information doesn't just have the power to shock – it can actually kill someone. In this case, the surprise that a husband isn't dead after all is more deadly than a railroad accident. Ideas have to be communicated carefully, with preparation and delicacy. Otherwise, the listener may very well end up dead.
If the Mallards had been better communicators throughout the marriage, perhaps the husband's shocking return from the dead wouldn't have killed his wife.
The fact that Mr. Mallard doesn't die, in spite of the fact that Richards got confirmation from a second source, reinforces the imperfection of any long-distance communication.