Right atrium enlargement predicts clinically significant supraventricular arrhythmia in patients with pulmonary arterial hypertension.

BACKGROUND: Right atrial (RA) enlargement is a common finding in patients with pulmonary arterial hypertension (PAH) and an important predictor of mortality, however its relation to the risk of atrial arrhythmias has not been assessed.

OBJECTIVES: To assess whether RA enlargement is associated with supraventricular arrhythmias (SVA) and whether it predicts new clinically significant SVA (csSVA).

METHODS: Patients with PAH were recruited between January 2010 and December 2014 and followed until January 2017. csSVA was diagnosed if it resulted in hospitalization. To assess predictors of new csSVA, only patients without a history of SVA at baseline were analyzed.

RESULTS: Among 97 patients, any SVA was observed in 45 (46.4%) and included permanent atrial fibrillation(AF, n = 8), paroxysmal AF (n = 10), permanent atrial flutter (AFl, n = 1), paroxysmal AFl (n = 2) or other types of supraventricular tachycardia (n = 24). Patients with SVA as compared to patients without SVA were characterized by older age, lower distance in a 6-minute test, higher NT-proBNP, higher RA area index (RAai), left atrial area index, mean right atrial pressure (mRAP) and were more commonly treated with β-blocker. Eighty five patients who were in sinus rhythm at baseline assessment and had no history of significant SVA were observed for 37 ± 19.9 months. During that time csSVA occurred in 15.3%. In univariate models, the occurrence of csSVA were predicted by age, right ventricular ejection fraction, right ventricular end diastolic index, RAai and mRAP, but in multivariate model only RAai remained significant predictor for csSVA (HR of 1.23, 95%CI: 1.11-1.36, p < 0.001). The optimal threshold for RA enlargement as discriminator of csSVA was 21.7 cm2/m2.

CONCLUSIONS: In PAH patients RA enlargement is associated with increased prevalence of SVA. RAai is an independent predictor of hospitalization due to csSVA.