Impact of Etiology on the Left Atrial Function in Patients with Severe Mitral Regurgitation

Abstract

Background: Adaptation to chronic volume overload in patients with mitral insufficiency (MI) tends to increase left atrium (LA), leading to LA dysfunction and arrhythmias. Though LA dimension is a well-known cardiovascular risk predictor, LA contractile function has not been thoroughly assessed in patients with MI of distinct etiologies. Objective: We aimed to assess LA structure and function in patients with MI due to rheumatic heart disease (RHD) and mitral valve prolapse (MVP). Methods: We assessed 54 patients with severe MI, defined by an effective regurgitant orifice (ERO) ≥ 0.40 cm2, 23 with RHD and 31 with MVP, all in sinus rhythm and with left ventricular (LV) ejection fraction > 60%. We measured LV diameters and mass, and also volumes (Simpson) to assess function, including maximal, minimal and pre-atrial contraction volumes, and total (TLAEF), passive (PLAEF) and active (ALAEF) LA emptying fraction. Transmitral and tissue Doppler measurements were obtained. Results: Compared to MVP, patients with RHD were younger (35 ± 11 versus 55 ± 13 years) and mainly female (17 versus 7 female; p < 0.05); LV mass index was higher for MVP patients. Although LA maximal volume was similar for both groups, patients with RHD had higher minimal LA volumes (56.9 ± 30 versus 41.6 ± 17 ml; p = 0.02), resulting in lower TLAEF (0.41 ± 0.11versus 0.47 ± 0.07; p = 0.03) and ALAEF (0.20 ± 0.08 versus 0.27 ± 0.07; p < 0.001). Conclusion: Although younger, patients with MI due to RHD present with more severe LA dysfunction compared to MVP, possibly reflecting direct atrial impairment from rheumatic heart disease. (Arq Bras Cardiol: Imagem cardiovasc. 2016;29(1):3-10)