Atrial Fibrillation (A Fib) Causes

      Atrial fibrillation may occur without evidence of underlying heart disease. This is more common in younger people, about half of whom have no other heart problems. This is often called lone atrial fibrillation. Some of the causes that do not involve the heart include the following:

•  Hyperthyroidism (overactive thyroid)

• Alcohol use (holiday heart or Saturday night heart; a condition of A fib, supraventricular tachycardia, or other cardiac arrhythmia usually triggered by some holiday-related event such as increased alcohol drinking or discontinuing medications; the condition often subsides once the triggering behavior is ceased)

• Pulmonary embolism (a blood clot in the lungs)

• Pneumonia 

      Most commonly, atrial fibrillation occurs as a result of some other cardiac condition (secondary atrial fibrillation).

• Heart valve disease: This condition results from developmental abnormalities people are born with or can be caused by infection or degeneration/calcification of valves with age.

• Enlargement of the left ventricle walls: This condition is called left ventricular hypertrophy. 

• Coronary heart disease (or coronary artery disease): This results from atherosclerosis, deposits of fatty material inside the arteries that cause blockage or narrowing of the arteries, interrupting oxygen delivery to the heart muscle (ischemia).

• High blood pressure: This condition is known as hypertension. 

• Cardiomyopathy: This disease of the heart muscle leads to congestive heart failure.

• Sick sinus syndrome: This refers to improper production of electrical impulses because of malfunction of the SA node in the atrium of the heart.

• Pericarditis: This condition refers to inflammation of the sac surrounding the heart. 

• Myocarditis: This condition causes inflammation of the heart muscle. 

•  Advancing age: The older a person is above age 40, the higher the risk. 

      Atrial fibrillation frequently occurs after cardiothoracic surgery or procedures, but often resolves in a few days.
      For many people with infrequent and brief episodes of atrial fibrillation, the episodes are brought on by a number of triggers. Because some of these involve excessive alcohol intake or skipping medications, this is sometimes called "holiday heart "or "Saturday night heart." Some of these people are able to avoid episodes or have fewer episodes by avoiding their triggers. Common triggers include alcohol and caffeine in susceptible individuals.