The irony in Kate Chopin's "The Story of an Hour" is what frames this short story with Chopin's motif of heart problems in Mrs. Mallard. In the opening line, Chopin writes, "Knowing that Mrs. Mallard was afflicted with a heart trouble...." Ironically, this heart trouble is not physical as the reader first suspects; rather it is spiritual, the ache of a repressed spirit in Mrs. Mallard. After she is told that her husband has died and she retires to the privacy of her bedroom, Louise Mallard senses a release of her spirit as she looks out the open window of the room. Considering the new freedom that she can now possess, Louise Mallard's pulses beat faster and she comes alive with her sense of release. But, after she rises joyously from her chair and descends the stairs carrying herself "like a goddess of Victory," she sees her husband standing by the front door, and, then, ironically, Louise Mallard dies of another heart trouble: "of the joy that kills"--the realization that her new-found freedom, her new joy, has been stolen.
In Chopin's "The Story of an Hour," the woman is expected to feel badly about her husband's death. The other characters are worried that her heart trouble could cause a problem because she is shocked and hurt by her husband's death. And they worry about her becoming too distraught when she is by herself in her room.
In actuality, the opposite of all of the above happens. That's irony.
Her initial reaction to the death of her husband is what's expected, but not for long. Instead, she feels a release, a sense of freedom. Her subservience to her husband is over, and she rejoices. Her heart causes her trouble when she finds out her husband is still alive, not when she hears that he is dead. And she is anything but distraught. During her time alone in her room, she discovers a sense of freedom she, apparently, has not felt for a long time.
Chopin uses plot, character thoughts and dialogue, imagery, and symbolism to construct the story and reveal its irony.