Acute Coronary Syndrome (ACS): This is often the first consideration for chest pain, especially if the pain is described as squeezing, pressure, or heaviness in the chest, radiating to the arm, neck, or jaw, and associated with shortness of breath, nausea, or diaphoresis. The high prevalence of coronary artery disease and the potential for serious outcomes make ACS a top priority.

Gastroesophageal Reflux Disease (GERD): Chest pain that worsens with lying down or after eating, and is relieved by antacids, suggests GERD. The pain is often described as burning.
Musculoskeletal Pain: Pain that is sharp, localized to a specific area, and exacerbated by movement or deep breathing is suggestive of musculoskeletal origin, such as costochondritis or muscle strain.
Pulmonary Embolism (PE): While not as common as ACS, PE should be considered, especially in patients with risk factors such as recent travel, immobilization, or family history of clotting disorders. Symptoms include sudden onset of chest pain that worsens with deep breathing, along with shortness of breath.
Pneumonia or Pleuritis: Infections or inflammation of the lung tissue or pleura can cause chest pain, typically sharp and worsened by deep breathing or coughing.

Aortic Dissection: A life-threatening condition where the inner layer of the aorta tears. Pain is often severe, tearing, and radiates to the back. High blood pressure and aortic aneurysm are risk factors.
Pulmonary Embolism (also listed under Other Likely Diagnoses): Due to its potential for being deadly if missed, it's crucial to consider PE in any patient with unexplained chest pain, especially if there are associated symptoms like tachypnea or tachycardia.
Esophageal Rupture: Severe, constant chest pain that worsens with swallowing, associated with vomiting or difficulty breathing, suggests an esophageal rupture, which is a medical emergency.

Pericarditis: Inflammation of the pericardium, the sac surrounding the heart, can cause sharp, stabbing chest pain that improves with sitting up and leaning forward. It's less common but can be associated with viral infections or autoimmune diseases.
Pneumothorax: Air in the pleural space can cause sudden, sharp chest pain and shortness of breath. It's more common in tall, thin males or those with lung disease.
Esophageal Spasm: Abnormal muscle contractions of the esophagus can cause chest pain that mimics cardiac pain but is often associated with difficulty swallowing.