Abstract
Heart failure (HF) with preserved ejection fraction (HFpEF) is diagnosed by symptoms and/ or markers of congestion with cardiac dysfunction despite 'normal' (preserved) left ventricular (LV) EF. Of the criteria, left atrial volume (LAV) is being increasingly used, with cardiovascular magnetic resonance (CMR) recognised as the gold standard for volumetric assessment. We searched databases for studies with LAV and indexed (LAVi) measurements obtained through both transthoracic echocardiography (TTE) and CMR. We identified 17 articles, encompassing 1203 individuals with cardiac disease. TTE showed more frequent measurement failure (6% [95% CI 2, 11]) compared to CMR (1% [0, 5]). TTE underestimated values compared to CMR, with a bias of -20mL [95% CI -30, -11] for LAV and - 9 mL/m(2) [95% CI -13, -5] for LAVi (p < 0.001). TTE misclassified LA enlargement in 38% [95%CI 25, 52) of cases diagnosed by CMR. TTE systematically underestimates LAV and should be used with caution.