Demographic and clinical characteristics
All 355 COVID-19 patients’ clinical information was collected and evaluated. As shown in Table 1, common case, defined as oxygenation index higher than 300, was 213 (60.0%). For severe case, whose oxygenation index was from 200 to 300, was 90 (25.4%). For critically ill case, whose oxygenation index was lower than 200, accounted for 14.6% (Table 1). Moreover, the demographic characteristics were then analyzed. As shown in Table 2, 162 (45.6%) were female and 193 (54.4%) were male. There were 96 patients younger than 39 years old, 144 patients aged between 40 and 59, and 115 patients older than 60 years old. Of 355 patients with COVID-19, 230 (64.8%) patients had hypertension, 208 (58.6%) patients had diabetes and 20 (5.63%) had chronic heart disease.
Association of myocardial injury with the severity of COVID-19 patients
The association between myocardial injury and the severity of COVID-19 was evaluated in patients. Myocardial injury indexes, including CK, CKMB, LDH and AST,were analyzed. As shown in Table 1, the level of CK were higher in critical ill patients than those of mild and severe patients. The number of CKMB-positive patients were more in critical ill patients than those of mild patients. The levels of LDH and AST were the lowest in the mild patients with COVID-19. Moreover, the levels of LDH and AST were higher in the critical ill patients than those of in severe patients. Myocardial injury was defined as any of myocardial functional indexes beyond normal range. The results indicated that 114 (53.5%) COVID-19 patients were with myocardial injury at early stage in mild patients. 61 (67.8%) patients with myocardial injury were in severe patients and 45 (86.5%) patients with myocardial injury were in critically ill patients. Furthermore, the associations between oxygenation index and myocardial injury markers were analyzed. As shown in Supplemental Table 1, no association between CK and CKMB with oxygenation index was observed, there was a negative association between AST (r=-0.249, P = 0.001) and LDH (r=-0.431, P༜0.001) with oxygenation index among COVID-19 patients. Additionally, the associations between inflammatory cytokine and myocardial injury markers were analyzed. The results indicated that CRP was positively correlated with AST (r = 0.241, P = 0.004), LDH (r = 0.457, P༜0.001) and CK (r=-0.198, P = 0.018) (Supplemental Table 1).
Male elderly COVID-19 patients with hypertension are more vulnerable to myocardial injury
The effects of demographic characteristics on myocardial injury markers were analyzed. As shown in Table 2, the level of CK were higher in males than in females. There was no different of CKMB, LDH and AST between females and males. Further analysis showed that CK, CKMB, LDH and AST were lower in patients younger than 39 years old than those of older patients. Moreover, we found that CK, CKMB, LDH and AST were higher in patients older than 60 than those between 40 from 59 years old (Table 2). The effects of comorbidities on myocardial functional indexes were then analyzed. As shown in Table 2, CKMB-positive patients were more in COVID-19 patients with hypertension than those without hypertension. Besides, the level of CK was elevated in COVID-19 patients with diabetes compared with those without diabetes. LDH and AST were increased in COVID-19 patients with chronic heart disease compared with those without heart disease. In addition, the risk factors of myocardial injury were analyzed using multivariable logistic regression among COVID-19 patients. As shown in Table 3, the OR of male gender was 2.012 (95% Cl: 1.125, 3.599), the OR of age was 1.434 (95% Cl: 1.041, 1.976) and the OR of hypertension was 3.393 (95% Cl: 1.441, 7.989) for myocardial injury, respectively.
Myocardial injury at early stage elevates death risk of COVID-19 patients
The effects of myocardial injury at the early stage on death risk are presented in Table 4. Among 220 COVID-19 patients with myocardial injury, 10.4% were died. The fatality rate was higher among COVID-19 patients with myocardial injury than those without myocardial injury (15.0% vs 1.74%; RR = 8.625, 95% Cl: 2.107, 35.305; P < 0.001).
Myocardial markers remain abnormal 14 days after discharge
The recovery of myocardial injury markers was investigated in every patient with COVID-19. Myocardial markers were compared between on admission and 14 days after discharge in the Second People’s Hospital of Fuyang City. As shown in Table 5, there was no significant difference in the levels of CK, CKMB and AST among COVID-19 patients between on admission and after discharge, whereas LDH was decreased on 14 days after discharge than on admission. On admission, 5 (3.3%) cases with CK, 9 (6.1%) cases with CKMB, 56 (38.1%) cases with LDH and 19 (12.3%) cases with AST were above the normal range. In all, there was 68 (44.2%) COVID-19 patients with myocardial injury. The prognosis of COVID-19 patients’ myocardial injury markers was followed up 14 days after discharge in the Second People’s Hospital of Fuyang City. We found that 2 (1.33%) patients with CKMB, 25 (16.7%) patients with LDH and 25 (15.3%) patients with AST remained above the normal range. Further analysis showed that 32 (21.3%) patients with COVID-19 continuously accompanied with myocardial injury 14 days after discharge (Table 5).