ObjectiveThe prognostic value of left atrial (LA) dimensions may differ between patients with and without atrial fibrillation (AF).MethodsMEDLINE and EMBASE were searched for studies that investigated the association between LA echocardiographic parameters measured by transthoracic echocardiography and cardiovascular outcomes in patients with or without AF. Data were independently abstracted by two reviewers and pooled using random-effects meta-analysis. The primary outcome was incident stroke or thromboembolic events. Secondary outcomes were heart failure, all-cause mortality and major adverse cardiac events (MACE).ResultsTwenty-three studies of patients with AF (14 939 patients) and 68 studies of patients without AF (50 720 patients) in this systematic review. Increasing LA diameter was significantly associated with stroke and thromboembolic events in patients without AF (risk ratio (RR) 1.38, 95% CI 1.02 to 1.87; p=0.03), but not in patients with AF (RR 1.02, 95% CI 0.98 to 1.07; p=0.27; p for difference=0.05). Increasing LA diameter index was significantly associated with MACE in patients with AF (RR 1.13, 95% CI 1.09 to 1.17; p<0.001) and in patients without AF (RR 2.98, 95% CI 1.90 to 4.66; p<0.001), with stronger effects in non-AF populations (p for difference <0.001). Greater LA volume index was significantly associated with the risk of MACE in patients with AF (RR 1.01, 95% CI 1.00 to 1.02; p=0.03) and in non-AF populations (RR 1.08, 95% CI 1.05 to 1.10; p<0.001), the association being stronger in individuals without AF (p for difference <0.001).ConclusionsLarger LA parameters were associated with various adverse cardiovascular events. Many of these associations were stronger in individuals without AF, highlighting the potential importance of LA myopathy.