key: cord-0878502-5lsoe267 authors: Zhou, Wenqian; Song, Ling; Wang, Xiang; Xu, Zheng; Wang, Shudong; Wang, Jiqun; Xu, He; Zheng, Yang; Wang, Yushi title: Cardiac injury prediction and lymphocyte immunity and inflammation analysis in hospitalized patients with coronavirus disease 2019 (COVID-19)() date: 2020-10-22 journal: Int J Cardiol DOI: 10.1016/j.ijcard.2020.10.049 sha: 462342263ba4a7c22640930f31ff214f7d919a7d doc_id: 878502 cord_uid: 5lsoe267 BACKGROUND: Coronavirus disease 2019 (COVID-19) is an ongoing global pandemic. The ability to predict cardiac injury and analyze lymphocyte immunity and inflammation of cardiac damage in patients with COVID-19 is limited. We aimed to determine the risk factors and predictive markers of cardiac injury in these patients. METHODS: Data from 124 consecutive hospitalized patients with confirmed COVID-19 were collected. We compared the proportion of cardiovascular disease history in moderate, severe, and critical cases. We obtained high-sensitivity cardiac troponin I (hs-cTn I) results from 68 patients. Patients were divided into two groups based on positive hs-cTn I result: those with cardiac injury (n = 19) and those without cardiac injury (n = 49). RESULTS: Compared with the group with moderate disease, hypertension, coronary heart disease, and smoking were more common in severe and critical cases. Diabetes mellitus was most common in the critical group. Age older than 65 years, presence of chronic kidney disease, and lower blood lymphocyte percentage were independent risk factors of cardiac injury. The total T- and B-lymphocyte counts and CD4+ and CD8+ T-cell counts were significantly lower in those with cardiac injury. A minimal lymphocyte percentage < 7.8% may predict cardiac injury. The interleukin (IL) 6 level in plasma was elevated in the group with cardiac injury. CONCLUSIONS: The lymphocyte percentage in blood may become a predictive marker of cardiac injury in COVID-19 patients. The total T and B cells and CD4+ and CD8+ cell counts decreased and the IL-6 level increased in COVID-19 patients with cardiac injury. Coronavirus disease 2019 (COVID-19) is a worldwide pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and many patients have died across the globe. The outbreak was declared a Public Health Emergency of International Concern on January 30, 2020, by the World Health Organization (WHO). Although most patients with COVID-19 have respiratory symptoms, reports have suggested that coronavirus can also cause acute cardiac injury [1] [2] [3] . The demand for greater understanding of the clinical characteristics of cardiovascular injury in COVID-19 and its associated risk factors and mechanisms is increasing. The aim of this study was to compare the minimal levels of lymphocyte percentage during the disease to determine whether these values could predict cardiac injury. We retrospectively collected data from 124 hospitalized patients with COVID-19 at Tongji Hospital of Tongji Medical College Hua Zhong University of Science & Technology-Zhongfa Division, China, from January 28, 2020, including medical history, clinical manifestation, laboratory findings, complications, and outcomes data. The proportions of moderate, severe, and critical cases with hypertension were 13.6%, 43.5%, and 50%, respectively (p˂0.05). The proportions of patients with diabetes were 13.6%, 22.6%, and 50%, respectively (p˂0.05). The proportion of patients with coronary heart disease were 2.3%, 11.3%, and 11.1%, respectively (p˂0.05), and the proportion of those who smoked in each group were 2.3%, 19.4%, and 16.7%, respectively (p˂0.05). Thus, hypertension, coronary heart disease, and smoking were more common in severe and critical cases. Diabetes was more common in critical cases than in the other two groups (p˂0.05) (Supplementary Figure 1 ). We collected the hs-cTn I results of 68 patients, including 16 (24%) moderate cases, 36 (56%) severe cases, and 16 (24%) critical cases. The median peak levels of hs-cTn The study included 68 hospitalized confirmed COVID-19 cases with hs-cTn I results. The hs-cTn I level higher than 14 pg/mL was considered positive. Patients were divided into two groups according to the hs-cTn I results: with cardiac injury (n=19, 28%) and without cardiac injury (n=49, 72%). The proportion of patients older than 65 years was significantly higher in those with cardiac injury than in those without cardiac injury. Moreover, patients with cardiac injury were more likely to have diabetes and chronic kidney disease (CKD), but not other comorbidities, including smoking, hypertension, coronary heart disease, chronic liver disease, chronic respiratory disease, thyroid disease, cancer, and influenza. Regarding laboratory findings, lymphocyte percentage and minimal lymphocyte percentage were much lower in patients with cardiac injury than in those without cardiac injury. Elevated interleukin (IL) 6 and creatinine were higher in those with cardiac injury than in those without cardiac injury. In addition, the N-terminal pro-B-type natriuretic peptide level was much higher in those with cardiac injury than in those without cardiac injury (Table 1) . Patients with cardiac injury were more common in the critical group. Moreover, patients with cardiac injury required more non-invasive and invasive mechanical ventilations. More patients had multiple-organ dysfunction syndrome and died in the group with cardiac injury than in the group without cardiac injury (Table 1) . J o u r n a l P r e -p r o o f Journal Pre-proof patients Risk factors that were significantly different in the two groups were analyzed by multivariable logistic regression, including age, diabetes, chronic kidney disease, lymphocyte percentage, minimal lymphocyte percentage, creatinine, and IL-6. Age ≥65 years, CKD, and minimal lymphocyte percentage were independent risk factors for cardiac injury (Supplementary Table 1 ). The blood lymphocyte percentages (%) were compared at four main time points (days 1, 8, 18, and 23, ±2 days) after admission ( Figure 1A ). The lymphocyte percentage in the group with cardiac injury was significantly lower than that in the group without cardiac injury at four time points ( independent risk factor of cardiac injury, and the lymphocyte percentage in peripheral blood could predict cardiac injury. (3) Immunological analysis suggested that cardiac injury was mainly associated with the decrease in T and B lymphocytes. (4) The level of the inflammatory biomarker IL-6 was elevated in the group with cardiac injury. Reports have suggested that SARS-CoV-2 can cause cardiac injury, which aggravates the disease and leads to a worse prognosis [5] [6] [7] . An autopsy report of a patient with COVID-19 showed degeneration and necrosis of myocardial cells as well as infiltration of a few monocytes, lymphocytes, and/or neutrophils in the interstitium [8] . The underlying mechanisms of cardiac injury are still not very clearly understood. We summarized the possible mechanisms as follows: (1) The most likely mechanism is angiotensin-converting enzyme 2 (ACE2)-associated signaling involved in cardiac injury [5] . ACE2 is involved in heart function, diabetes, and hypertension and plays a potential protective role for the heart by negatively regulating the renin-angiotensin system. SARS-CoV-2 enters human cells by glycoprotein binding to ACE2 receptors of the host cell surface. (2) The virus causes an immune system aberration and cytokine storm [9] . (3) Severe and critical cases always have hypoxemia, which leads to acidosis, an increase in intracellular free radicals, and calcium overload. This may be another mechanism of cardiac injury. In our study, the results showed that diabetes and hypertension were more often found in severe or critical cases. This might be explained by a direct endocrine link among diabetes, hypertension, and ACE2. ACE2 plays a role in maintaining cardiovascular homeostasis [10] . ACE2 could degrade angiotensin II (Ang II) into J o u r n a l P r e -p r o o f Journal Pre-proof angiotensin 1-7. When ACE2 activity is inhibited, Ang II plays a pro-inflammatory role and increases blood pressure. On the other hand, angiotensin 1-7 exerts anti-inflammatory and anti-fibrosis function. Patients with severe and critical COVID-19 were more likely to have diabetes and hypertension, probably because of an imbalance in the ACE2-associated pathways [11] . Our results suggest that severe and critical cases were more likely to have coronary heart disease. This may be associated with an increase in ACE2 secretion in these patients [5] . The high level of ACE2 made individuals particularly susceptible to SARS-CoV-2. Besides the lung and heart, ACE2 is also expressed in the kidney [12]; hence, people with CKD might be more vulnerable to infection. We showed that a history of diabetes was related to cardiac injury, which can be explained by ACE2 activity levels being elevated in the pancreas and diabetes inducing ACE2 expression in other tissues, such as the heart and lung [13] . Therefore, diabetes can contribute to damage of other organs in COVID-19 patients, including the heart [11] . However, after infection, SARS-CoV-2 reduces ACE2 activity and consumes the receptors [14] ; hence, the ACE2/Ang II balance is disturbed and the heart may not be protected anymore, resulting in cardiac injury. This might be the reason why patients with underlying cardiovascular disease were more prone to infection and exhibited severe and critical disease, especially cardiac injury due to ACE2. Lymphocytes play an important role in immune homeostasis and inflammatory response. Our results showed that the lymphocyte percentage decreased significantly with cardiac injury. A minimal lymphocyte percentage in peripheral blood <7.8% Journal Pre-proof could predict a high risk of cardiac injury in patients with COVID-19. This will be helpful for physicians to judge the heart condition of patients. The probable mechanism of lymphopenia is the presence of ACE2 receptors in lymphocytes, which can be a target for SARS-CoV-2. The virus may also destroy immune organs. An inflammatory response leads to the release of pro-inflammatory cytokines, which in turn reduces the lymphocyte count. Furthermore, patients with cardiac injury were mostly severe and critical cases, with accompanying hyperlacticacidemia, which could inhibit the proliferation of lymphocytes [15] . Data from other reports have suggested that older adults were more susceptible to COVID-19, and aging is strongly associated with infection fatality in COVID-19 [16] . Our results showed that age ≥ 65 years was a risk factor for cardiac injury. A possible mechanism of cardiac injury is through immune function disruption. The immune system of older patients undergoes many age-related changes, known as immune senescence [17] . Lymph nodes, which produce naive T and B cells, become less able to maintain naive T cells and differentiation in the final third of life. B cells also undergo a similar reduction but much more slowly than T cells [18] . This is consistent with the immunological analysis results in this study, which suggested that the numbers of T and B lymphocytes were significantly decreased in the group with cardiac injury, but the decreased proportion of B lymphocytes did not differ. Another problem in the immune system is that T cells cannot move quickly to -fight‖ due to dysregulation of chemokines, which guide T-cell migration. Therefore, aging is associated with cardiac injury, probably due to immune senescence. Journal Pre-proof SARS-CoV-2 infection can cause inflammatory cytokine storms in the immune system. In this study, we compared several inflammatory biomarkers between the groups with and without cardiac injury. The IL-6 level was elevated in the group with cardiac injury, but this was not the case with other biomarkers. The reason might be because cardiac damage was related to aging and immune dysregulation. Thus, the inflammatory response was not as strong in older people as it was in younger people. However, the inflammatory response was still excessive and active at an early stage. Our results showed that more patients had CKD and elevated levels of creatinine in the blood in the group with cardiac injury than in the group without cardiac injury. Therefore, we considered that cytokine overproduction was involved in kidney-heart bidirectional damage in COVID-19 patients. Previous reports suggested that COVID-19 patients with diabetes are affected by a low-grade inflammation that facilitates the cytokine storm, and IL-6 was more elevated in COVID-19 patients with diabetes than in those without diabetes [19] . Therefore, we thought that diabetes resulted in metabolic inflammation and cytokine storms that damaged the heart further. In addition, the imbalance and loss of ACE2 might aggravate the inflammatory cytokine storm [20]. There are some limitations to our study. First, it was a single-center study and the number of patients was not very large. Second, we lacked some echocardiographic information and so did not include echocardiography results. Third, the prognosis in hospital is limited, and we did not follow-up. In conclusion, the risk factors for cardiac injury in COVID-19 patients include not J o u r n a l P r e -p r o o f Journal Pre-proof only aging but also chronic diseases such as diabetes and CKD. These factors affect the immune system and cause an inflammatory response, which damages the heart further. Lymphopenia is an effective marker that might be able to predict cardiac injury in COVID-19 patients and help physicians estimate disease conditions. 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