ABSTRACT
BACKGROUND: The left atrium (LA) in the transplanted heart (TH) is a surgically created chamber from variable portions of donor and recipient LA. The American Society of Echocardiography (ASE) recommends measuring LA size in native hearts using biplane LA volume index (LAVI) as a more accurate measurement than LA anterior-posterior diameter (LA-APD). We hypothesized that LA-APD underestimates LA size when compared with LAVI in the TH. METHODS: Patients with a TH from 1/05 to 1/10 who had a transthoracic echocardiogram within 24 months of transplant were studied. Patients were excluded if they had an ejection fraction <50%, left ventricular hypertrophy, >mild aortic or mitral regurgitation, or poor image quality. Echocardiograms were analyzed for LA-APD and LAVI. LA size was classified as normal, mild, moderate, or severely enlarged based on age and sex specific cutoffs per the ASE. RESULTS: Of 297 patients evaluated, 160 met inclusion criteria. Mean age was 57 ± 13 years and 79% were males. Mean LA-APD and LAVI were 4.3 ± 0.6 cm and 36 ± 14 mL/m(2), respectively. LAVI correlated with LA-APD (r = 0.43, R(2) = 0.18, P < 0.0001). By LA-APD measurement, 20 (13%) LA were classified as having moderate or severe LA enlargement versus 80 (50%) by LAVI, P = 0.001. LA size was underclassified by ≥ 2 classes in 44 (28%) by LA-APD versus LAVI. CONCLUSIONS: In the setting of cardiac transplant, the LA size classified by LA-APD is commonly less than that classified by LAVI.