Effect of atrial fibrillation on exercise capacity in mitral stenosis

Left atrium reservoir function is central in patients with rheumatic mitral stenosis

We investigated the relationship between Left Atrium strain reservoir function and symptoms and its impact on modulating Left Ventricular mechanics, diastolic filling, stroke volume, mean trans-mitral gradient and pulmonary pressure in mitral stenosis (MS) patients. We examined 195 full spectrum MS patients which were divided into two groups: Group 1 (n = 109) included patients with NYHA I & II functional class and group 2 (n = 86) included patients with NYHA III & IV functional class. LA strain reservoir function and classical echocardiographic parameters were calculated. LASr was significantly higher in group 1 versus group 2 in patients with MVA ≤ 1cm2 [8.8(6.0-12.6) vs 6.8(4.1-8.9), p = 0.03) and when 1cm2 < MVA ≤ 1.5 cm2 [10.0 (5.4-13.8) vs 6.7(4.5-9.0), p = 0.02). In patients with Pulmonary Hypertension, group 1 had significantly higher LASr than group 2 [11.1(6.6-14.8) vs 5.9(4.3-9.0), p = 0.002) By multivariate analysis, diabetes (OR = 4.11, 95%CI: 1.6-10.4), stroke (OR = 2.9, 95%CI: 1.1-7.9), LASr (OR = 0.9, 95%CI: 0.80-0.99) and LV ejection fraction (LVEF)(OR = 0.9, 95%CI: 0.91-0.99) were independently associated with NYHA functional class. LASr was significantly and positively correlated to MVA (r = 0.3, p < 10-3), stroke volume (r = 0.25, p = 10-3), mitral inflow (r = 0.4, p < 10-3) and LVEF(r = 0.14, p = 0.05). It was significantly and negatively correlated to left ventricular strain (r = -0.65, p < 10-3), LA indexed volume (r = -0.40, p < 10-3), maximum tricuspid regurgitation velocity (r = -0.25, p = 0.003), MTMG (r = -0.25, p = 10-3), and heart rate (r = -0.4, p < 10-3). We demonstrated a large range of interaction between LASr and mitral valve echocardiographic parameters. This may explain the reasons we identified LASr as an independent factor for MS functional tolerance.