Chest pain or pressure (especially radiating to arm, jaw, or back)
Sudden shortness of breath or difficulty breathing
Palpitations (fast, irregular, or skipped beats)
Unexplained dizziness, fainting, or weakness
Rapid or severe changes in blood pressure
Oxygen saturation < 90% despite oxygen support
Excessive sweating, nausea, or vomiting
Sudden swelling in the ankles, feet, or abdomen
Changes in mental status (confusion, restlessness, anxiety)
