Here's why:
* Psychological Tension: The story focuses on the narrator's mental state and the escalating terror he experiences, building suspense through his internal struggle and growing paranoia.
* Slow Build-Up: Poe gradually introduces details and reveals the narrator's murderous act, creating a sense of anticipation and dread.
* Suspenseful Moments: The story is filled with moments that keep the reader on edge, such as the narrator's meticulous planning of the murder, his heightened senses, and the constant repetition of the beating heart.
* Unreliable Narrator: The narrator's unstable mental state adds to the suspense, as the reader questions the truth of his claims and the reality of the situation.
Overall, "The Tell-Tale Heart" is a masterfully crafted suspense story that plays with the reader's emotions and keeps them captivated until the very end.