Differential Diagnosis for Syncope Preceded by Throat Tightness and Left Arm Pain

Single Most Likely Diagnosis

• Acute Coronary Syndrome (ACS): This is the most likely diagnosis given the symptoms of throat tightness and left arm pain preceding syncope. These symptoms are classic for myocardial ischemia or infarction, which can lead to decreased cardiac output and subsequently cause syncope.

Other Likely Diagnoses

• Aortic Dissection: Pain in the arm and throat tightness could be indicative of an aortic dissection, especially if the pain is severe and tearing in nature. Syncope can occur due to involvement of the aortic arch or obstruction of major arteries.
• Pulmonary Embolism (PE): While less common, a large PE could cause sudden onset of chest pain or discomfort (potentially referred to the arm) and syncope due to obstruction of major pulmonary arteries leading to decreased cardiac output.
• Cardiac Arrhythmias: Certain arrhythmias, such as ventricular tachycardia or supraventricular tachycardia, can cause syncope. Throat tightness might be less directly related but could be part of a broader symptom complex including palpitations and chest discomfort.

Do Not Miss Diagnoses

• Esophageal Rupture: Although rare, an esophageal rupture could present with severe chest pain and potentially syncope. The throat tightness could be related to the esophageal pathology.
• Hypertrophic Cardiomyopathy: This condition can cause syncope, especially with exertion, and might be associated with chest pain. However, throat tightness is less commonly a presenting symptom.
• Takotsubo Cardiomyopathy: Also known as "stress cardiomyopathy," this condition can mimic ACS and cause syncope. Emotional or physical stress could precipitate symptoms.

Rare Diagnoses

• Subclavian Steal Syndrome: A rare condition where there is a significant stenosis or occlusion of the subclavian artery, leading to reversal of blood flow in the vertebral artery. This could potentially cause syncope and arm pain but is less likely to cause throat tightness.
• Cervical Spine or Neurological Causes: Certain neurological conditions, such as vertebral artery dissection or cervical spine instability, could potentially cause syncope and arm pain. However, these would be less common and might have additional neurological symptoms.