Differential Diagnosis

The patient's symptoms of fainting, fatigue, shortness of breath on exertion, and palpitations, combined with the medical history and test results, suggest a range of potential underlying causes. Here is a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Aortic Stenosis: The patient's symptoms of fainting (syncope), fatigue, and shortness of breath on exertion are classic for aortic stenosis, especially in the context of a prolonged PR interval and dropped QRS on EKG, which may indicate conduction abnormalities associated with severe aortic stenosis. The elevated BNP further supports heart failure, which can be a consequence of severe aortic stenosis.

• Other Likely Diagnoses

  • Heart Block: Given the EKG findings of a prolonged PR interval and dropped QRS, heart block (particularly Mobitz Type II or complete heart block) is a plausible diagnosis. This condition can lead to symptoms of fainting, fatigue, and palpitations due to inadequate cardiac output.
  • Hypothyroidism-related Cardiomyopathy: The patient's elevated TSH indicates hypothyroidism, which can lead to cardiomyopathy and heart failure, explaining the shortness of breath, fatigue, and elevated BNP.
  • Coronary Artery Disease: Although the patient's blood pressure readings do not significantly change with position, suggesting no orthostatic hypotension, the history of hyperlipidemia and smoking increases the risk for coronary artery disease, which could lead to heart failure and arrhythmias.

• Do Not Miss Diagnoses

  • Cardiac Amyloidosis: This condition can present with heart failure, arrhythmias, and conduction abnormalities. It's crucial to consider, especially given the patient's age and symptoms of heart failure (elevated BNP).
  • Pulmonary Embolism: Although less likely given the chronic nature of symptoms, pulmonary embolism can cause sudden onset of shortness of breath and syncope. It's a diagnosis that cannot be missed due to its high mortality rate if untreated.
  • Arrhythmias (e.g., Sick Sinus Syndrome, AV Node Dysfunction): These conditions can cause palpitations and syncope. Given the EKG abnormalities, it's essential to consider and rule out these arrhythmias.

• Rare Diagnoses

  • Carcinoid Heart Disease: This condition can lead to heart valve abnormalities, particularly tricuspid and pulmonary valve disease, resulting in heart failure symptoms. It's rare but should be considered in the differential diagnosis of unexplained heart failure.
  • Fabry Disease: A genetic disorder that can lead to cardiomyopathy and heart failure. It's rare and typically presents at a younger age but can be considered in the differential diagnosis of unexplained cardiomyopathy.