Relationship Between Cardiac and Liver Markers with In-hospital Mortality in COVID-19 Patients

Abstract
Background: COVID-19 caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections has turn into a pandemic and has extended all over the world. Since the virus has the potential ability to severely impair heart and liver, analyzing the biochemical parameters is a suitable approach for clinicians to assess the outcome.
Methods: This study was conducted along with 614 recognized COVID-19 patients. All samples were from Emergency department of Sina Hospital in Tehran, Iran, from February to May, 2020.
Results: A total of 614 COVID-19 patients with mean age of 57.8 years (16-94 years) consisting of 385 (62.7%) male and 229 (37.2%) female were studied. Patients with COVID-19 had no significant difference between cardiac and liver parameters on the presentation and discharge time (p-value≥0.05). Patients with COVID-19 had significant correlation in Lactate dehydrogenase (LDH), Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Alkaline phosphatase (ALP), and Total Bilirubin with recovery and mortality outcome (p-value≤0.05). Also, high sensitivity cardiac Troponin-I, LDH, AST, and ALT in patients with COVID-19 were significantly associated with high in-hospital mortality (p-value<0.05).
Conclusion: Several laboratory parameters may ease the evaluation of COVID-19 in-hospital mortality. Cardiac and liver parameters are critical in assisting COVID-19 cases.
Keywords: COVID-19, Cardiac, Liver, Mortality 

Introduction
Severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) is a new pathogen responsible for the new extensively known corona virus disease 2019 (COVID-19). The basis of managing is supportive care and no well-known treatment is available. Mortality  statistics for the situation show a discrepancy, with a reported overall mortality rate among 1.4 and 2.3% (1). World Health Organization (WHO) reported more than 162 million established cases and over 3.3 million deaths across the world, up to 17 May 2021 (2). This number to be 3.5, about 56 million people in Iran will be infected (3). The contributing function of paraclinical including laboratory data is far beyond etiological recognition and it is now approximately obvious that these laboratory findings are efficiently concerned in epidemiologic surveillance, prediction of prognosis, patient follow-up, including COVID-19 (4). Since the virus has potential ability of severely damaging some vital organs such as heart, liver, and kidneys, analyzing the laboratory parameter is a proper way for clinicians to assess these organs’ functions (5). Some laboratory data may aid the consideration of COVID-19 severity to select mild from severe COVID-19 disease (6). The role of COVID-19 in initiating pro-inflammatory condition has been well-known (7). Therefore, paraclinical evaluations include laboratory data play a main role in early diagnosis and treatment observation of COVID-19 (8). Infections, hospitalizations, and deaths are different among countries, prompting the question in relation to which patients are at higher risk and why (9). Also, most of these studies pay attention to the symptoms and radiologic findings, with only inadequate concentration on laboratory data, which could be useful in the diagnosis and determination of severity of COVID-19. Only data from observational studies is accessible. Therefore, it is required to summarize the laboratory findings in each study, the consequences of which can support the diagnosis and treatment of the disease in each country (10). There is restricted data obtainable describing the paraclinical findings of Iranian patients. Thus, we assessed cardiac and liver parameters on presentation and discharge time in our country to reveal the probable diversity with other countries and relationship with poor outcome and the need to intensive care. In this study, the laboratory markers were also summarized that might be useful in indicating in-hospital mortality in COVID-19 patients.

Materials and Methods
Study population and setting
This cross-sectional study was conducted on 614 recognized COVID-19 patients over 18 years of age, who referred to Emergency Department in Sina Hospital in Tehran in Iran affiliated to Tehran University of Medical Sciences and a government-designated hospital for COVID-19 treatment. From February to May 2020, patients with respiratory signs, fever, and weakness who suspected to COVID-19 infection (11) with positive COVID-19 result by Polymerase Chain Reaction (PCR) were included (12). Also, according to the Iranian national committee of COVID-19, we enrolled the highly suspicious patients with a compatible chest computed tomography (CT) scan findings with COVID-19 (13). Patients with incomplete laboratory data due to transfer to other hospitals were excluded.

Data collection
Data including age, sex, and duration of hospitalization was gathered from the electronic medical records. Blood samples were collected from each participant and creatine kinase isoenzyme (CPK), creatine kinase isoenzyme‐MB (CK‐MB), and high sen-sitivity cardiac troponin-I (cTnI) in the serum were measured using standard assay kit and Siemens ADVIA Centaur XP automatic chemiluminescence immunoassay analyzer for all the patients according to the manufacturer’s instructions. Furthermore, liver enzymes such as Aspartate aminotransferase (AST), Alanine aminotransferase (ALT), Alkaline phosphatase (ALP) as well as Bilirubin (Total and Direct), Albumin and lactate dehydrogenase (LDH) in the serum were assessed using standard assay kit by Mindray BS-200 automated biochemistry analyzer. Laboratory data were recorded within 24 hours of admission and time of discharge or death.
The study protocol was approved by the Ethics Committee of Tehran University of Medical Sciences (ethical code: IR. TUMS.SINA HOSPITAL.1399.009). 

Statistical analysis
All analyses were done by using the Statistical Package of Social Science Software (SPSS version 20; IBM Company) and p-value level of 0.05 or below was described as statistically significant. Categorical variables were presented in percentage (%) while continuous data were reported as mean ± SD. Dependent upon the nature of variable, Chi-square, Fisher’s exact tests, Mann–Whitney U Test, or independent t test were used as proper, to evaluate the patients’ laboratory data on presentation and discharge time. The accuracy of diverse laboratory parameters in predicting cases with COVID-19 positive patients was assessed by Area under the ROC curve (AUC).

Results
From 647 hospitalized patients, 33 (5.1%) patients with incomplete date were excluded. Among 614 patients, the mean age was 57.8 years (18-64years) which consists of 385 (62.7%) male and 229 (37.3%) female. Average period of hospitalization was 5.06 (0-55) days (Table 1).

Table 1. Demographic data with recovery and in-hospital mortality outcome

Laboratory parameters.

Table 2 compares the cardiac and liver parameters of patients with COVID-19 on presentation and discharge time. Patients with COVID-19 had no significant difference between cardiac and liver parameters on presentation and discharge time (p-value≥0.05). Table 3 compares the cardiac and liver parameters of COVID-19 patients with recovery and mortality outcome. Patients with COVID-19 had significant correlation in LDH, AST, ALT and Total Bilirubin recovery and mortality outcome (p-value≤0.05).

Table 2. Comparison of the cardiac and liver parameters of COVID-19 patients at presentation and discharge time

Table 3. Comparison of the cardiac and liver parameters of COVID-19 patients with recovery and mortality outcome

The ROCs were calculated to assess the associations between cardiac and liver parameters and mortality. cTnI, LDH, AST, and ALT in patients with COVID-19 had significant correlation with mortality (p-value<0.05). Cardiac and liver parameters of patients with COVID-19 had significant correlation with mortality (Table 4).

Table 4. Cardiac and liver parameters of patients with COVID-19 had significant correlation with mortality

Discussion
Four months after the first cluster of cases were reported in Wuhan, China, coronavirus disease 2019 (COVID-19) persisted as a major cause of morbidity and mortality worldwide (14). Several laboratory parameters may facilitate the assessment of disease severity (6). Due to the rapid spread of the COVID‐19 pandemic, affected countries have taken a heterogeneous and evolving approach to diagnosis of infection in patients and continue to have different strategies, and every country needs to evaluate the COVID-19 patients’ findings (15).
A series of recently published studies have reported the epidemiological and clinical characteristics of patients with COVID-19 disease, but data regarding the laboratory characteristics of infected individuals are limited (16). In the Zhang et al study, of the 4,663 patients included, the most prevalent laboratory finding was increased C-reactive protein, followed by decreased albumin, increased erythrocyte sedimentation rate, and increased LDH. Also, meta-analysis of seven studies with 1905 patients showed that increased CRP and LDH were significantly associated with severity. These results demonstrated that more attention is warranted when interpreting laboratory findings in patients with COVID-19 (10). Also, there were significant increases in creatinine, CPK, LDH, and potassium levels between ICU-admitted and non-ICU patients (17). Therefore, one of predominant laboratory findings was LDH elevation (18). 
COVID-19 is causing considerable morbidity and mortality worldwide. Serious respiratory complications aside, the heart is also frequently involved. The mechanisms and the extent of the myocardial injury in COVID-19 survivors remain unclear (19). Since the first data analyses in China, elevated cardiac troponin has been noted in a substantial proportion of patients, implicating myocardial injury as a possible pathogenic mechanism contributing to severe illness and mortality. Accordingly, high troponin levels are associated with increased mortality in patients with COVID-19 (20). In a recent study summarizing clinical course of patients with COVID-19, detectable cTnI was observed in most patients, and cTnI was significantly elevated in more than half of the patients died (21). Risk with elevated cTnI is independent of baseline cardiovascular disease (22). These findings were correlated with our data and observed in our population. 
Furthermore, serum LDH was validated for its potential usefulness as markers for evaluating clinical severity and monitoring treatment response in COVID-19 pneumonia. It was demonstrated that increase or decrease of LDH was indicative of disease progress or improvement (23). Our data was similar and we demonstrated increased cTnI and LDH and significant relationship with mortality. Thus, careful monitoring of the cardiac enzyme profiles is of great importance in reducing the complications and mortality in patients with COVID‐19 (24). Evidence from the Chinese cohort suggests that patients demonstrate high C-Reactive Protein (CRP) and less common elevations in liver enzymes ALT and AST (25) which was similar to our findings. Pazoki et al reported a considerable percentage of admitted patients who presented with cardiac, liver, and kidney impairment (26). Furthermore, in a systematic analysis of 11 articles, Lippi and Plebani have documented laboratory abnormalities reported in cases of COVID-19. Patients may also present with decreased albumin, or increases in LDH, total bilirubin, and also cTnI (27). Patients with abnormal liver tests were at higher risk of progressing to severe disease. Also, we showed liver enzymes related to mortality. The detrimental effects on liver injury were mainly associated with certain medications used during hospitalization, which should be monitored and evaluated frequently (28). Bilirubin levels have been found altered in patients with Covid‐19, but the dynamics of such alteration are not clear, especially in relation to the severity of the disease (29).
Some studies demonstrated that serum albumin analysis may be useful to identify patients at higher risk of death in COVID-19 patients (30). A low albumin level can potentially lead to early recognition of severe disease and assist clinicians in making informed decision for their patients (31). Chen et al found that LDH had significantly increased in most patients, while albumin had decreased, but ALT and AST showed no significant changes (32). In agreement, Huang et al introduced decreased albumin along with increased LDH, ALT, and total bilirubin levels as appropriate biomarkers with the ability to discriminate between severe and non-severe groups (33). Between these markers, we revealed the correlation among AST, ALT, total bilirubin, LDH, and cTnI with mortality. But, relationship between Albumin level and mortality was not observed in our population which may be due to the disparity in race.
Our study had some limitations. The study population was small and included only patients from Sina Hospital, one of the main hospitals in Iran. There may be a selection bias when identifying factors that differ between patients even though the results were adjusted for known confounders, including age, sex, race, and comorbidities. Also, some patients presented elevated biomarker data in some laboratory measures, and they were not excluded from the analysis due to the small sample size and because those numbers were physiological and not due to the technical errors. Further studies including more cases and ancillary tests are necessary to elucidate the mechanism of disease progression and fatal outcome. 

Conclusion
The present study suggests that liver and cardiac measurement could predict outcome and in-hospital mortality associated with COVID-19. Thus, it is necessary to continue these measures. There is an increased urgent need to detect new biomarkers in order to identify cases of COVID-19 that will evolve unfavorably. These biomarkers must be easy to measure and accessible to most hospitals such as liver and cardiac markers that manage COVID-19 cases and determine in-hospital mortality.

Ethics approval
The study protocol was approved by the Ethics Committee of Tehran University of Medical Sciences (ethical code: IR. TUMS.SINA HOSPITAL.1399.009). Participants were informed about the components of the study and its objectives upon entering the study. The current research was conducted in accordance with the Declaration of Helsinki.

Data availability
The data of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions. All authors were equally involved in preparing the manuscript (Conceptualization and design of the study, searching for articles, writing the final draft, etc.). 

Acknowledgements
We acknowledge all health-care workers involved in the diagnosis and treatment of patients in Sina Hospital. We are indebted to the Research Development Center of Sina Hospital for its support. The authors are grateful to Mrs. Masoumeh Taleh and Mr. Saeed Hejrani for their help and members of the COVID-19 Crisis Committee of Sina Hospital for their help and consultation.

Conflict of Interest
None declared.

Funding
None.