Differential Diagnosis for New Onset Atrial Fibrillation (AF)

Single Most Likely Diagnosis

• Hypertension: This is often the most common cause of new onset AF due to the high prevalence of hypertension in the population and its direct effects on the heart, including left atrial enlargement and fibrosis, which predispose to AF.

Other Likely Diagnoses

• Coronary Artery Disease: Myocardial ischemia or infarction can trigger AF, making CAD a likely cause, especially in patients with risk factors for atherosclerosis.
• Heart Failure: Both reduced and preserved ejection fraction heart failure can lead to AF due to increased atrial pressure and stretch.
• Thyroid Disease: Hyperthyroidism, in particular, is a well-known cause of AF, although hypothyroidism can also contribute to arrhythmias.
• Alcohol Use (Holiday Heart Syndrome): Binge drinking can precipitate AF in some individuals, even in the absence of underlying heart disease.
• Obstructive Sleep Apnea: This condition is increasingly recognized as a risk factor for AF, possibly due to intermittent hypoxia and increased sympathetic tone.

Do Not Miss Diagnoses

• Pulmonary Embolism: Although less common, PE can cause new onset AF and is a medical emergency requiring prompt diagnosis and treatment.
• Cardiac Tamponade: This condition, characterized by fluid accumulation in the pericardial sac, can lead to AF among other symptoms and signs, and is life-threatening if not promptly addressed.
• Myocarditis or Pericarditis: Inflammation of the heart muscle or pericardium can precipitate AF and requires specific treatment.
• Toxic or Medication-Induced Causes: Certain medications (e.g., theophylline, bronchodilators) and toxins (e.g., cocaine) can trigger AF.

Rare Diagnoses

• Cardiac Sarcoidosis: A condition where granulomatous inflammation affects the heart, potentially leading to AF among other arrhythmias.
• Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC): A rare heart muscle disorder that can cause AF, although it more commonly causes ventricular arrhythmias.
• Mitral Stenosis: While more commonly associated with AF in the context of rheumatic heart disease, mitral stenosis can still be a cause in regions where rheumatic fever is prevalent.
• Cardiac Tumors: Rarely, primary or metastatic cardiac tumors can cause AF by interfering with normal cardiac conduction and function.