Main features of COVID-19 patients have been reported in the literature. While young patients under 45 years old (y/o) account for a non-negligible part of hospitalized patients, data on this population remain sparse.

To describe the characteristics and outcomes of hospitalized COVID-19 young patients (<45 y/o).

The Critical COVID France (CCF) study was an observational multicenter study including patients hospitalized for COVID-19. Primary composite outcome included transfer to ICU or in-hospital death. Secondary outcomes were cardiovascular complications diagnosed by the referring medical team according to available clinical, biological and radiological findings.

Among 2,878 patients hospitalized for COVID-19 in 24 centers, 321 (11.2%) patients were under the age of 45 y/o. They had a higher body mass index (BMI) (28.9±6.6 vs 27.7±6.0, P=0.004) but less other cardiovascular risk factors including hypertension (29 (9.2%) vs. 1422 (56.1%), P<0.001), diabetes (20 (6.3%) vs. 656 (25.9%), P<0.001) and dyslipidemia (15 (4.7%) vs. 783 (30.7%), P<0.001). The primary outcome occurred in 54 (16.8%) patients under 45 y/o vs. 783 (30.7%) in patients aged >45 y/o (P<0.001), with a strong impact on the death rate (3 (0.9%) vs. 358 (14.0%), P<0.001). The group under 45 y/o experienced more frequently related COVID-19 cardiovascular complications such as pericarditis (12 (0.5%) vs. 7 (2.2%), P=0.003) and myocarditis (14 (0.6%) vs 8 (2.5%), P=0.002). Conversely, acute heart failure occurred more frequently in patients aged >45 y/o (183 (7.2%) vs. 3 (0.9%), P<0.001). Acute coronary syndrome and stroke were similar between the two groups (Fig. 1).

In this nationwide multicenter observational study of hospitalized COVID-19 patients, patients under the age of 45 y/o had less cardiovascular risk factors but more specific related COVID-19 cardiovascular complications such as pericarditis and myocarditis.