Differential Diagnosis for Palpitations

The patient's symptoms of palpitations, chest tightness, lightheadedness, and anxiety, which resolved spontaneously, suggest a range of possible diagnoses. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Panic Attack or Anxiety Disorder: The patient's symptoms of palpitations, chest tightness, lightheadedness, and anxiety are classic for a panic attack. A Generalized Anxiety Disorder–7 (GAD-7) score of 6 would support this diagnosis, indicating mild anxiety. The normal examination, laboratory studies, and EKG in the ED further point towards a primary psychiatric cause rather than a cardiac one.

• Other Likely Diagnoses

  • Supraventricular Tachycardia (SVT): Although the EKG was normal at the time of the ED visit, P waves hidden in the QRS complex on a subsequent Holter monitor tracing could indicate SVT, which can cause palpitations and anxiety.
  • Mitral Valve Prolapse: This condition can cause palpitations and chest discomfort. Mitral valve prolapse seen on an echocardiogram would confirm this diagnosis, although it's less likely given the absence of murmurs on examination.

• Do Not Miss Diagnoses

  • Hyperthyroidism: An elevated TSH level (though more commonly, hyperthyroidism is associated with a low TSH level) could indicate thyroid dysfunction, which can cause palpitations, anxiety, and other symptoms the patient experienced. It's crucial to consider and rule out thyroid disorders due to their significant impact on the cardiovascular system.
  • Cardiac Arrhythmias: Other arrhythmias not initially detected could be responsible for the patient's symptoms. Although less likely given the normal initial EKG, further monitoring or testing might be warranted to rule out conditions like atrial fibrillation or ventricular arrhythmias.

• Rare Diagnoses

  • Atherosclerotic Disease: Atherosclerotic plaque seen on carotid ultrasonography would be unusual in a 35-year-old without significant risk factors for atherosclerosis. This finding would not directly explain the patient's acute symptoms of palpitations and anxiety.
  • Other Cardiac Anomalies: Rare cardiac conditions, such as hypertrophic cardiomyopathy or arrhythmogenic right ventricular cardiomyopathy, could potentially cause the patient's symptoms but would be less likely without additional findings on examination or initial diagnostic tests.