A 71-year-old man wakes in the middle of the night, gasping for air. Paramedics rush to save him, but it's all in vain: he's dead by the time they arrive. What caused his death?A 71-year-old man wakes in the middle of the night, gasping for air. Paramedics rush to save him, but it's all in vain: he's dead by the time they arrive. What caused his death?