Differential Diagnosis for Palpitations

The patient's symptoms of heart racing, chest tightness, lightheadedness, and anxiety, which resolved spontaneously, suggest a range of possible diagnoses. Here's a categorized differential diagnosis based on the provided information:

• Single Most Likely Diagnosis

  • Anxiety or Panic Disorder: The patient's symptoms of palpitations, chest tightness, lightheadedness, and anxiety, especially in the context of driving and having to stop the car, are highly suggestive of a panic attack. A GAD-7 score of six supports this diagnosis, as it indicates mild anxiety, which is consistent with the presentation.

• Other Likely Diagnoses

  • Hyperthyroidism: An elevated TSH level could indicate hyperthyroidism, which can cause palpitations, anxiety, and other symptoms the patient experienced. However, the normal labs from the ER visit might not fully support this unless the thyroid function tests were not comprehensive or were done at a time when thyroid hormone levels were not elevated.
  • Mitral Valve Prolapse: Microdrop out prolapse on echo could be a finding in mitral valve prolapse, a condition that can cause palpitations, chest discomfort, and anxiety in some patients. However, it's less directly linked to the acute symptoms described.

• Do Not Miss Diagnoses

  • Arrhythmias (e.g., Supraventricular Tachycardia): Heat waves hidden in the QRS complex on a subsequent Holter monitor tracing could indicate an arrhythmia. Although the initial EKG was normal, intermittent arrhythmias might only be detected with prolonged monitoring. Missing this diagnosis could lead to significant morbidity if the arrhythmia is not properly managed.
  • Cardiac Structural Abnormalities: While less likely given the normal initial evaluation, conditions like hypertrophic cardiomyopathy or other structural heart diseases could present with similar symptoms and would be critical not to miss due to their potential for severe outcomes.

• Rare Diagnoses

  • Atherosclerotic Disease: Given the patient's age and the absence of risk factors mentioned, atherosclerotic disease causing coronary artery disease is less likely but cannot be entirely ruled out without further evaluation. An uncrowded ultrasound might not be directly relevant to the diagnosis of coronary artery disease but could refer to a vascular study; however, this seems out of context for the primary complaint.
  • Other rare cardiac conditions, such as Wolff-Parkinson-White syndrome or cardiac sarcoidosis, could also present with palpitations but would be less likely given the information provided and the normal initial evaluations.