Differential Diagnosis

The patient's symptoms of fainting, fatigue, shortness of breath, and palpitations, along with the laboratory and EKG findings, suggest a cardiac origin for his symptoms. Here is a categorized differential diagnosis:

• Single most likely diagnosis
  • Tachycardia-Bradycardia Syndrome: This condition, also known as sick sinus syndrome, is characterized by episodes of both tachycardia and bradycardia. The patient's EKG shows sinus bradycardia, and telemetry monitoring reveals episodes of atrial fibrillation with rapid ventricular rates, which is consistent with this diagnosis. The patient's symptoms of fainting, fatigue, and palpitations can be explained by the alternating episodes of tachycardia and bradycardia.
• Other Likely diagnoses
  • Complete Heart Block: The patient's EKG shows prolonged PR intervals and dropped QRS complexes, which suggests a conduction abnormality. Complete heart block could explain the patient's bradycardia and fainting episodes.
  • Primary Autonomic Dysfunction: The patient's symptoms of fainting, fatigue, and orthostatic changes in blood pressure could be related to autonomic dysfunction. However, this diagnosis would not fully explain the cardiac findings on EKG and telemetry monitoring.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Anterior Myocardial Infarction: Although the patient's troponin level is only slightly elevated, an anterior myocardial infarction could still be present, especially if the patient has a non-ST-elevation myocardial infarction (NSTEMI). This diagnosis would require immediate attention and treatment.
  • Right Bundle Branch Block with Bifascicular Block: The patient's EKG shows a right bundle branch block, and the presence of a bifascicular block (right bundle branch block with left anterior or left posterior fascicular block) could increase the risk of complete heart block.
• Rare diagnoses
  • Cardiac Amyloidosis: The patient's elevated brain natriuretic peptide (BNP) level and symptoms of fatigue and shortness of breath could suggest cardiac amyloidosis. However, this diagnosis would require further evaluation, including echocardiography and cardiac biopsy.
  • Infiltrative Cardiomyopathy: The patient's symptoms and EKG findings could also suggest an infiltrative cardiomyopathy, such as sarcoidosis or hemochromatosis. However, these diagnoses would be less likely and would require further evaluation.