IJCS | Volume 31, Nº6, November / December 2018

575 Table 3 - Patients with reduction in left atrial mechanics in the reservoir phase Reduction in left atrial mechanics in the reservoir phase p Yes (7/16 - 44%) No (9/16 - 56%) Age, years 67 [66 - 73] 77 [69 - 81] 0.09 Permanent atrial fibrillation 4/7 (57%) 8/9 (89%) 0.26 CHA 2 DS 2 -VASc 5 [3 - 5] 5 [4 - 6] 0.35 HAS-BLED score 3 [2 - 4] 3 [2 - 3] 0.92 Cardiac plug device size, mm 24 [22 - 25] 24 [21 - 25] 0.83 Baseline mildly abnormal LVEF 0/0 3/9 (33%) 0.09 Baseline left atrium volume, mL 41 [33 - 45] 46 [40 - 62] 0.27 Baseline left atrium emptying fraction, % 25 [13 - 49] 18 [15 - 39] 0.43 Baseline global Ɛ R, % 14.4 [8.7 - 26.4] 9.2 [5.6 - 14.0] 0.14 Baseline global SR R , s -1 1.1 [0.9 - 1.2] 1.0 [0.8 - 1.1] 0.25 LVEF: left ventricle ejection fraction; Ɛ R: left atrium strain during the reservoir phase; SR R : left atrium strain rate reservoir phase. Comparison of variables was performed with a Mann-Whitney test and SR R values by the t-test. Data expressed as mean and standard deviation or median and interquartile range. Madeira et al. Atrial appendage closure and atrial performance Int J Cardiovasc Sci. 2018;31(6)569-577 Original Article closely following left atrial physiology, and can be used to evaluate dynamic left atrial function. 18,19 It has also been demonstrated that the left atrial reservoir Ɛ R is associated with fibrosis and can thus represent left atrial stiffness. 21 Contrary to earlier belief, LAA is now thought to play an important role in normal cardiac hemodynamics, acting as an adaptive chamber in conditions of volume overload to attenuate the rise in intra-atrial pressure. 22,23 Furthermore, the highest density of atrial natriuretic- peptide granules of the heart is found in LLA, and the release of atrial natriuretic peptide with consequent diuresis is an important compensatory mechanism involved in themaintenance of normal fluidhomeostasis. 24 Hondo et al., 23 in a study performed in 10 open-chest dogs, reported that the LAA is more compliant than the left atrial main chamber. They also found a higher dimensional increase in the LAA than the left atrial main chamber during left atrial volume overload. Davis et al., 25 reported, in a study using 6 isolated canine left atria, that the LAAmay enable the entire left atrium to better adapt reservoir function to physiologic conditions by protecting the pulmonary capillary system from encountering a rise in pressure. In a study conducted by Kamohara et al., 26 to investigate the short-term and midterm effects of LAA exclusion on left atrial function, involving 19 dogs with 90 days of follow-up, the authors showed no significant difference in the transmitral flow tissue Doppler imaging measurements, left atrial pressure, left ventricular volume, or stroke volume. Tabata et al., 27 evaluated the role of LAA in left atrial reservoir function by assessing changes in left atrial flow dynamics after LAA clamping during cardiac surgery. The subjects of the study were 8 patients who had undergone coronary artery bypass grafting and 7 who had undergone valvular surgery for mitral regurgitation; all patients were in sinus rhythm. They demonstrated that, in both groups, mean left atrial pressure andmaximum left atrial dimension significantly increased during LAA clamping. The authors concluded that the LAA is more compliant than the left atrial main chamber and plays an important role in left atrial reservoir function. Johansson et al., 28 explored the effects on atrial and ventricular function of restoring sinus rhythm after epicardial cryoablation and closure of the LAA in 65 patients with mitral valve disease and atrial fibrillation. In patients who were in sinus rhythm, peak velocity during atrial contraction and the reservoir function were lower in patients that underwent LAA closure than in the control group at 6 months of follow- up. In summary, it seems that in patients who are in sinus rhythm, LAA occlusion might negatively influence left atrial reservoir function. In fact, our patients in sinus rhythmhad a decrease in Ɛ R and SR R after the procedure. However, in patients with atrial fibrillation, closure of the LAA does not seem to have an impact on left atrial reservoir function. Hanna et al., 29 conducted a study designed to evaluate the effects of percutaneous LAA transcatheter occlusion on anatomic and hemodynamic properties of the mitral valve and left upper pulmonary vein in 10 patients with atrial fibrillation. At 6 months of follow-up, left superior pulmonary vein diameter, peak systolic and diastolic flow velocities, left atrial size, severity of mitral regurgitation, and mitral valve peak E-wave velocity showed no significant change from baseline. In our sample, patients at baseline had decreased left atrial reservoir function, which was expressed by