Aims Cardiac complications are common and associated with mortality in critically ill patients with COVID-19; however, the diagnostic and prognostic implications of critical care echocardiography (CCE) have not been studied. Methods and results A cohort of 43 patients with COVID-19 who were in the intensive care unit (ICU) underwent bedside CCE during their disease course. Demographic, clinical, and survival data were collected. The echocardiographic analyses revealed high frequencies of pericardial effusion (90.7%), increased left ventricular mass index (60.5%), elevated relative wall thickness (76.7%), and reduced left ventricular stroke volume index (LVSVi; 53.5%) and cardiac index (51.2%). Twenty-two (51.2%) patients died in the ICU. In multivariate Cox regression, the strongest predictor of in-ICU death was decreased cardiac index [hazard ratio (HR), 0.67, 95% confidence interval (CI), 0.45-0.98; P = 0.041], after adjusting for male sex, shock status, high-sensitivity cardiac troponin I, and N-terminal pro-B-type natriuretic peptide. Negative associations with mortality were observed for LVSVi (HR, 0.91, 95% CI 0.85-0.96; P = 0.002), tricuspid annular plane systolic excursion (HR, 0.74, 95% CI 0.64-0.84; P < 0.001), and S′ (HR, 0.78, 95% CI 0.69-0.88; P < 0.001). Kaplan-Meier analyses indicated that reductions in LVSVi, cardiac index, TAPSE, and S′ were associated with a shorter survival time. Conclusions Pericardial effusion and increased ventricular mass in COVID-19 might indicate a swollen heart. Both left and right heart dysfunction and a reduced cardiac index may lead to an increased risk of mortality. Clinicians should pay special attention to cardiac haemodynamic disorders in critical patients with COVID-19.