Right Atrial Enlargement Is Linked to Outcomes in Atrial Fibrillation

In a study of patients with nonvalvular atrial fibrillation (AF), right atrial enlargement was more significantly associated with clinical events than left atrial enlargement.

The findings could help improve risk stratification in the AF population, the investigators wrote in the Frontiers of Cardiovascular Medicine.

The heart has two upper chambers, the left atrium and the right atrium. Left atrial (LA) enlargement is associated with adverse cardiovascular events and is better understood than right atrial (RA) enlargement, hence the rationale for this study. LA enlargement is believed to occur because of AF or following shock (cardioversion) or ablative treatment for AF. Nonvalvular AF is AF without valve mechanical issues or a prosthetic valve.

“Little is known about the factors which can attribute to RA enlargement and the prognostic value of RA remodeling [enlargement] in patients with AF,” wrote Kyu-Yong Ko of the Division of Cardiology in the Department of Internal Medicine at Inha University College of Medicine, Incheon, South Korea, and his colleagues.

Investigators monitored patients with nonvalvular AF for a composite of events including hospitalization for heart failure, stroke, systemic embolism, or death from any cause. Patients were 69 years on average, and the study enrolled roughly twice as many men as women. RA enlargement was associated with older age and more frequent persistent (lasting 7 days or longer) or permanent AF.

At a median of 47.1 months, 77 patients (30%) had experienced one or more of the composite end points (events). The most common was stroke (16%), followed by hospitalization as the result of heart failure (15%). Two patients died.

The researcher reported that in patients with nonvalvular AF, RA enlargement was independently associated with increased risk of stroke, heart failure, systemic embolism, or death, “suggesting RA volume can be helpful to assessing future cardiovascular risk in this population.”

Investigators also said RA enlargement was associated with greater left ventricular mass and volume, higher systolic pulmonary atrial pressure, and “more significant” tricuspid regurgitation, which is reverse blood flow into the atrium caused by heart valve flaps that do not close properly.

In the separate analysis, female gender was strongly associated with HF hospitalization or all-cause death.

The prescription of anticoagulants was higher for patients with RA enlargement, but not statistically so. “In our study, the rhythm control strategy tended to yield better outcomes; however, it did not reach statistical significance probably due to the small number of patients with rhythm control,” investigators said.