Our findings are as follows: (1) COVID-19 patients with elevated TnI levels are at significantly higher risk of developing severe disease, requiring ICU admission, or death; (2) elevated CK, CK-MB, LDH, and IL-6 levels and emerging arrhythmia are associated with the development of severe disease or requirement for ICU admission; and (3) mortality rates are significantly higher among patients with elevated LDH and IL-6 levels. Here, IL6 is linked to cardiac arrhythmia.