Risk Factors That Contribute to the Maintenance of Sinus Rhythm (Afib)

Atrial fibrillation is the most commonly diagnosed arrhythmia in the United States. A systematic review of worldwide population-based studies estimated that approximately 33 million people were diagnosed with atrial fibrillation in 2010. The prevalence of atrial fibrillation in the United States increases with advancing age. Approximately 1% of patients with atrial fibrillation are under 60 years of age whereas more than one-third are over 80 years of age.

Although atrial fibrillation is commonly diagnosed and continues to have increased incidence in the country, patients continue to be admitted to the hospital for worsening symptoms of chest pain, shortness of breath, and palpitations. Long-term complications of atrial fibrillation include cardiomyopathy, cerebrovascular events, thromboembolic events, and death.

Many medications have been established to convert patients from atrial fibrillation to normal sinus rhythm; however procedures of cardioversion and ablation have also proven to be effective. A study, the AFFIRM trial, published in the New England Journal of Medicine in 2002 discussed the benefit of converting patients to sinus rhythm versus keeping patients in atrial fibrillation, however making sure their heart rates were well-controlled. This study did not demonstrate a significant difference in death, ischemic stroke, or major bleeding in both treatment arms suggesting there is no benefit of converting patients from atrial fibrillation to normal sinus rhythm. However, with increasing health costs occurring around the country, every effort should be made to help improve patient symptoms and avoid unnecessary hospitalizations. A study published in the Journal of American College of Cardiology in 2004, "Effect of rate or rhythm control on quality of life in persistent atrial fibrillation: Results from the Rate Control Versus Electrical Cardioversion (RACE) study," concluded that the quality of life was impaired in patients with atrial fibrillation. Another study published in 2012, "Economic Burden of Atrial Fibrillation: Implications for Intervention," reported total costs of atrial fibrillation care in the United States to be estimated to be $6.65 billion per year.

Our study is designed to look at patients with atrial fibrillation who underwent electrical cardioversion to restore sinus rhythm and create a prediction model to identify specific risk factors, which may contribute to persistent atrial fibrillation.

Prediction models have been established in regards to maintaining sinus rhythm, including the Hatch Score, which examined risk factors of hypertension, history of TIA or stroke, chronic obstructive pulmonary disease, and heart failure that predisposed patients to persistent atrial fibrillation. Another score established was the LADS score, which observed risk factors of left atrial diameter, age, history of stroke, and smoking status as predictors of persistent atrial fibrillation. The purpose of our study is to create a new prediction model using clinical and echocardiographic parameters to determine if these factors will predict persistent atrial fibrillation after electrical cardioversion. Transesophageal echocardiographic parameters include imaging of the left atrial appendage (LAA) and calculating the LAA ejection fraction (LAAEF) by 3D or biplane Simpson method (based on image quality), and using pulse-wave Doppler to calculate the LAA exit velocity and S/D ratio across the pulmonic vein. Transthoracic echocardiographic parameters include estimated pulmonary arterial pressure (PASP) using tricuspid regurgitation (TR) jet velocity, left atrial volume index (LAVi), left ventricular (LV) size, LV hypertrophy (LVH) and left ventricular ejection fraction (LVEF).