Inclusion criteria were observational case-control or cohort studies on COVID-19 patients with a history of CVD included, which reported outcomes of COVID-19 infection severity, clearly outlined the definition of “severe disease” and with sample size >10. Studies were divided into 2 separate cohorts for analysis: severity (severe vs nonsevere) and mortality (nonsurvivors vs survivors). The primary outcome of interest was the association between pre-existing CVD and COVID-19 severity. The secondary outcome was the association between underlying CVD and COVID-19 mortality. A tertiary outcome was the association between underlying CVD and mortality in patients with severe COVID-19 disease.