Table 3
Discussion Results of aforementioned studies underline how cardiac biomarkers, such as TnT, NT-pro-BNP and CK-MB are associated with severe form of COVID-19 infection. Above all, higher levels of these biomarkers are significantly associated with an increased risk of the mortality in COVID-19 infected patients (Table 4). Therefore, has been demonstrated COVID-19 infection is more severe in those patients with a previous history of arterial hypertension, cardiovascular diseases[8], [9], [13]–[15], [31]. In addition to classical laboratory parameters evaluated in COVID-19 infection, such as C Reactive Protein (CRP), D-Dimer, and lactate dehydrogenase (LDH), which are currently used in clinical practice, others biomarkers could potentially be useful for screening, clinical management, and prevention of serious complications.
Among the biomarkers mentioned above, the most important parameter to consider as a prediction of mortality is TnT. Infact the highest mortality was found in patients with progressively increasing troponin levels and a history of cardiovascular disease[8], [9], [31], [33].
Moreover, some pathophysiological bases have been hypothesized regarding the elevation of TnT levels in patients with COVID-19 infection: the instability of pre-existing atherosclerotic plaques resulting from the phenomenon of cytokine storm with a characteristic clinical picture of type 1 myocardial infarction[34], [35], a marked increase in oxygen demand by cardiomyocytes, in a situation of tissue hypoxia, with consequent ischemia that configures a picture of type 2 myocardial infarction[34] ; a direct myocardial damage with a picture of fulminant myocarditis (coronary artery disease)[36], [37] , effect of sepsis / cytokine storm and endothelial damage[38].
These hypotheses were proposed following the absence of viral genomes in cardiomyocytes and the presence of mononuclear inflammatory cells from autopsy findings[30].
Therefore, it is clinically significant that fluctuating levels of myocardial biomarkers are closely monitored and patients with high levels of myocardial biomarkers are treated promptly to improve prognosis[39]–[41]. At the end, on basis of symptoms and cardiac biomarkers patients could be divided as follows:
- Mild : patient has mild symptoms (fever, cough, headache, anosmia and / or ageusia) and possible or not pneumonia on X-Ray imaging with normal cardiac biomarkers.
- Severe : patient with respiratory distress, Respiratory Rate ≥ 30 beats/minute in a resting state, mean oxygen saturation ≤93%, and an arterial blood oxygen partial pressure (PaO2)/oxygen concentration (FiO2) ≤ 300 mm Hg with normal or high cardiac biomarkers.
- Critical : patient is characterized by respiratory failure and required mechanical ventilation, the occurrence of shock, and the combined failure of other organs that required Intensive Care Unit (ICU) monitoring and treatment with significantly elevated cardiac biomarkers[42], [43].