Background: Left atrial dilatation is a response to volume overload in chronic mitral regurgitation (MR). Left atrium volume index (LAVI) was associated with mortality, heart failure and atrial fibrillation in patients with MR. The authors do not know the association between LAVI and pulmonary artery pressure in patients with chronic severe primary MR.
Material and Method: The authors retrospectively studied patients with chronic severe MR (either one or both echocardiographic criteria of effective regurgitant orifice area > 40 mm2 or regurgitant volume > 60 ml by proximal isovelocity surface area method) who underwent transthoracic echocardiography at Siriraj Hospital between January 2005 and December 2009.
Results: A total of 181 patients (age 53.1 + 17.7 years, 53.6% male) were enrolled. Right ventricular systolic pressure (RVSP) tended to increase when LAVI increased (rs = 0.32, p < 0.001). The mean RVSP in 4 different quartiles of LAVI (< 48.80 ml/m2, 48.81-66.00 ml/m2, 66.01-97.40 ml/m2, > 97.40 ml/m2) were 41 + 14, 42 + 16, 44 + 16 and 56 + 18 mmHg, respectively. RVSP in patients with LAVI > 97.40 ml/m2 was significantly higher than those of the other 3 quartiles (p = 0.004). LAVI in patients with RVSP < 50 and > 50 mmHg were 74 + 53 and 116 + 82 ml/m2, respectively (p = 0.001).
Conclusion: In chronic severe primary MR, RVSP tends to increase when LAVI increases.

Keywords: Echocardiography, Left atrium volume, Chronic mitral regurgitation, Pulmonary hypertension