Abstract
Background: Current echocardiography practice is to apply international reference ranges (different by sex) to identify hypertrophy and dilatation. There is evidence that ethnicity influences heart size and ethnic-specific reference ranges have recently been developed within the New Zealand context.
Methods: Left ventricular mass (LVM) and relative wall thickness (RWT) were calculated from measurements recorded in the Hauora Manawa Community Heart Study. ASE and ethnic-specific normal ranges (NewERA) for these measures were used to characterise LV geometry into one of four groups (normal geometry, concentric remodelling, concentric hypertrophy and eccentric hypertrophy).
Results: There were 483 Māori (278 female) and 254 NZ European (130 female) participants in this analysis. Using ethnic-specific normal values resulted in less Māori hearts being classified with normal geometry, 336 (70%) to 290 (60%), while more had concentric remodelling 38 (8%) to 82 (17%). Concentric hypertrophy slightly increased, 33 (7%) to 51 (11%), while eccentric hypertrophy slightly decreased 76 (16%) to 59 (12%).
Changes were less pronounced in the NZ European group with slightly less normal geometry following the application of newERA values, 212 (83%) to 192 (76%). Most of this difference is accounted for by an increase in concentric hypertrophy, 11 (4%) to 28 (11%). Concentric remodelling, 18 (7%) to 16 (6%), and eccentric hypertrophy, 13 (5%) to 18 (7%) stayed relatively constant.
Discussion: The application of the ASE guidelines may result in the misclassification of heart disease in Māori patients, demonstrating the need to further investigate the clinical utility and prognostic implications of ethnic-specific normal ranges.