IMPAIRED LEFT ATRIAL FUNCTION AFTER HEART-TRANSPLANTATION - DISPARATE CONTRIBUTION OF DONOR AND RECIPIENT ATRIAL COMPONENTS STUDIED ONLINE WITH QUANTITATIVE ECHOCARDIOGRAPHY

Background: Because of a lack of noninvasive techniques, left atrial function after orthotopic heart transplantation has not been well characterized. Methods: Global left atrial performance and the relative contributions of donor and recipient atrial components were assessed with transthoracic echocardiography with on-line automated border detection in 20 patients with normal left ventricular systolic function 1 to 6 years (mean 3.5 +/- 0.3 years [standard error]) after heart transplantation. Results: The mean left atrial area at ventricular end-systole was 22.9 +/- 1.5 cm(2), the mean left atrial emptying fraction ([left atrial area at ventricular end-systole - left atrial area at ventricular end-diastole]/left atrial area at ventricular end-systole) was 29.7% +/- 2.6%, and the fractional area change caused by active contraction was 27.8% +/- 3.1%. Compared with controls, patients had larger atria, depressed emptying, and reduced fractional active contraction. Although the recipient to donor area ratio was 3:2, the proportion of atrial emptying (change in area from mid-to-late ventricular diastole divided by the total left atrial change during ventricular diastole) contributed by the recipient component was greatly diminished when compared with that of the donor component (1.4% +/- 3.5% versus 31% +/- 2.7%) (p = 0.0001). Conclusions: Despite being anatomically smaller, the functional contractile contribution of the donor component dominated atrial emptying. Thus, after heart transplantation, global left atrial function is depressed, predominantly because of dysfunction of the recipient atrial component.