Differential Diagnosis

The patient's complex presentation of symptoms, including "brain fainting," cardiac issues, desaturation, and gastrointestinal problems, requires a comprehensive differential diagnosis. The following categories outline potential diagnoses:

• Single Most Likely Diagnosis
  • Exertional Collapse Associated with Exercise (ECAE): This condition is characterized by collapse or near-collapse during or after intense exercise, often accompanied by symptoms such as nausea, vomiting, and shortness of breath. The patient's history of "brain fainting" episodes during running and the marathon incident align with ECAE. The condition can be related to dehydration, electrolyte imbalances, or cardiac issues, which may have contributed to the patient's abnormal ECG, troponin rise, and desaturation.
• Other Likely Diagnoses
  • Obstructive Sleep Apnea (OSA): Although the in-lab sleep study was normal, the at-home sleep test showed an AHI of 12, indicating mild OSA. The patient's desaturation during the stress test and overnight pulse ox test support this diagnosis.
  • Gastroesophageal Reflux Disease (GERD) or Functional Dyspepsia: The patient's history of stomachaches, chills, and discomfort after eating solid food, which resolved on its own, could be related to GERD or functional dyspepsia.
  • Cardiac Arrhythmia or Cardiomyopathy: The abnormal ECG, troponin rise, and desaturation during the stress test suggest potential cardiac issues, such as arrhythmias or cardiomyopathy, which may be contributing to the patient's symptoms.
• Do Not Miss Diagnoses
  • Pulmonary Embolism (PE): Although the patient's symptoms are not typical for PE, the desaturation and shortness of breath during exercise could be indicative of a PE, which would be a life-threatening condition if missed.
  • Cardiac Sarcoidosis: This condition can cause cardiac arrhythmias, heart failure, and desaturation, and may be related to the patient's abnormal ECG and troponin rise.
  • Myocardial Bridge: A myocardial bridge is a congenital condition where a portion of a coronary artery dives into and is surrounded by the myocardium, which can cause cardiac symptoms, including chest pain, shortness of breath, and arrhythmias.
• Rare Diagnoses
  • Mitochondrial Myopathies: These are a group of rare genetic disorders that affect the mitochondria, leading to muscle weakness, exercise intolerance, and other systemic symptoms, which could be related to the patient's "brain fainting" episodes and muscle symptoms.
  • Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT): This is a rare genetic disorder that can cause life-threatening arrhythmias during exercise or emotional stress, which may be contributing to the patient's cardiac symptoms.