Acute Myocardial Infarction (MI): This is the most likely diagnosis given the presentation of chest pain suggestive of MI. The symptoms of MI, such as chest pain or discomfort that may radiate to the arm, neck, or jaw, and possibly accompanied by shortness of breath, nausea, or fatigue, align closely with the classic presentation of an MI.

Angina Pectoris: This condition involves chest pain or discomfort due to transient myocardial ischemia without necrosis. It's a likely diagnosis because the symptoms can be very similar to those of an MI but are typically precipitated by exertion or emotional stress and relieved by rest or nitroglycerin.
Pulmonary Embolism (PE): While not directly related to myocardial ischemia, PE can cause sudden onset of chest pain, often described as sharp or stabbing, and can be life-threatening. The pain may worsen with deep breathing (pleuritic chest pain).
Acute Pericarditis: Inflammation of the pericardium can cause sharp, stabbing chest pain that may improve with sitting up and leaning forward. It's a consideration in the differential due to its potential to mimic MI symptoms.

Aortic Dissection: A life-threatening condition where there is a tear in the aorta's inner layer. The pain is often severe, tearing, and radiates to the back. Missing this diagnosis can be fatal, making it crucial to consider in any patient presenting with chest pain.
Pneumothorax: Air in the pleural space can cause sudden onset of sharp chest pain and shortness of breath. It's a critical diagnosis not to miss due to its potential for rapid progression to a life-threatening condition.
Esophageal Rupture: A rare but potentially fatal condition that can cause severe chest pain, often associated with difficulty swallowing or vomiting. The severity of the condition necessitates its inclusion in the differential diagnosis.

Chest Wall Syndrome (Costochondritis or Tietze's Syndrome): Inflammation of the cartilages and bones in the chest wall can cause sharp pains, but these are typically reproducible with palpation and movement.
Pulmonary Artery Hypertension: Elevated blood pressure in the pulmonary arteries can lead to right heart failure and cause chest pain among other symptoms, but it's less common and typically associated with other signs of right heart strain.
Mitral Valve Prolapse: A condition where the two valve flaps of the mitral valve do not close smoothly or evenly but instead bulge (prolapse) upward into the left atrium when the heart contracts. It can cause chest pain but is less commonly associated with the acute presentation of MI-like symptoms.