In this study, we aimed to identify the causes, predictors and gender disparities of 30-day and 90-day cardiovascular readmissions after COVID-19-related hospitalisations using National Readmission Database (NRD) 2020.
We used the NRD from 2020 to identify hospitalised adults with a principal diagnosis of COVID-19 infection.
We included subjects who were readmitted within 30 days and 90 days after index admission. We excluded subjects with elective and traumatic admissions. We used a multivariate Cox regression model to identify independent predictors of readmission.
Our outcomes were inpatient mortality, 30-day and 90-day cardiovascular readmission rates following COVID-19 infection.
During the study period, there were 1 024 492 index hospitalisations with a primary diagnosis of COVID-19 infection in the 2020 NRD database, 644 903 (62.9%) were included for 30-day readmission analysis, and 418 122 (40.8%) were included for 90-day readmission analysis. Of patients involved in the 30-day analysis, 7140 (1.1%) patients had a readmission within 30 days; of patients involved in the 90-day analysis, 8379 (2.0%) had a readmission within 90 days due to primarily cardiovascular causes. Cox regression analysis revealed that the female sex (aHR 0.89; 95% CI 0.82 to 0.95; p=0.001) was associated with a lower hazard of 30-day cardiovascular readmissions; however, congestive heart failure (aHR 2.45; 95% CI 2.2 to 2.72; p<0.001), arrhythmias (aHR 2.45; 95% CI 2.2 to 2.72; p<0.001) and valvular disease (aHR 2.45; 95% CI 2.2 to 2.72; p<0.001) had a higher hazard. The most common causes of cardiovascular readmissions were heart failure (34.3%), deep vein thrombosis/pulmonary embolism (22.5%) and atrial fibrillation (9.5%).
Our study demonstrates that male gender, heart failure, arrhythmias and valvular disease carry higher hazards of 30-day and 90-day cardiovascular readmissions. Identifying risk factors and common causes of readmission may assist with lowering the burden of cardiovascular disease in patients with COVID-19 infection.

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