key: cord-0870704-umfe40uo
authors: Ocak, Metin; Tascanov, Mustafa Begenc; Yurt, Nur Şimşek; Yurt, Yusuf Can
title: A new predictor for indicating clinical severity and prognosis in COVID-19 patients: Frontal QRS-T angle
date: 2021-09-23
journal: Am J Emerg Med
DOI: 10.1016/j.ajem.2021.09.046
sha: 544af63f87b42c35c0b301931344ac6ecb758e45
doc_id: 870704
cord_uid: umfe40uo

OBJECTIVE: COVID-19; It spread rapidly around the world and led to a global pandemic. Indicators of poor prognosis are important in the treatment and follow-up of COVID-19 patients and have always been a matter of interest to researchers. The aim of this study was to investigate the relationship between frontal QRS-T angle values and clinical severity and prognosis in COVID-19 patients. METHODS: This prospective case-control study was conducted with 130 COVID-19 patients whose diagnosis was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and 100 healthy controls. The CURB-65 score was used as the clinical severity score. RESULTS: A total of 130 patients and 100 healthy controls were included in the study. When the patient and control groups were compared a significant difference was found between QT (378.07 ± 33.75 vs. 368.63 ± 19.65, p < 0.001), QTc (410.79 ± 28.19 vs. 403.68 ± 11.70, p < 0.001), QRS time (95.04 ± 21.67 vs. 91.42 ± 11.08, p < 0.001) and frontal QRS-T angle (36.57 ± 22.86 vs. 22.72 ± 14.08, p < 0.001). According to clinical severity scoring, QT (370.27 ± 25.20 vs. 387.75 ± 40.19, p = 0.003), QTc (402.18 ± 19.92 vs. 421.48 ± 33.08, p < 0.001), frontal QRS-T angle (32.25 ± 18.79 vs. 41.94 ± 26.27), p = 0.0.16) parameters were found to be significantly different. Age (odds ratio [OR], 1.201; 95% confidence interval [CI], 1.111–1.298; p < 0.001) and frontal QRS-T angle ([OR], 1.045; 95% [CI], 1.015–1.075; p = 0.003) values were found to be an independent predictor for the severity of the disease. Frontal QRS-T angle ([OR], 1.101; 95% [CI], 1.030–1.176; p = 0.004), and CRP ([OR], 1.029; 95% [CI], 1.007–1.051; p = 0.01) parameters were found to be independent predictors for the mortality of the disease. As a mortality indicator; for the frontal QRS-T angle of ≥44.5°, specificity and sensitivity were 93.8% and 84.2%, respectively. CONCLUSION: Frontal QRS-T angle can be used as a reproducible, convenient, inexpensive, new and powerful predictor in determining the clinical severity and prognosis of COVID-19 patients.

Since it was first reported in Wuhan, China on December 31, 2019, the novel coronavirus has spread rapidly around the world, leading to a global pandemic [1] . The clinical spectrum of COVID-19 ranges from asymptomatic, mild or moderate respiratory 

This prospective case-control study was conducted with 130 COVID-19 patients whose diagnosis was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and 100 healthy controls. The control group consisted of people who were similar to the patient group in terms of demographic characteristics and comorbid factors. Ethical permission for the study was obtained from the local ethics committee. The study was carried out in Samsun Gazi State Hospital as a single center study. All patients over the age of 18 whose diagnosis was confirmed by RT-PCR and routine laboratory examination was requested were included in the study. Patients who had previous history of drug use that increased the frontal QRS-T angle value, patients who were previously diagnosed with COVID-19 and received treatment for COVID-19, had history of cardiac arrhythmia, were under the age of 18, had negative or suspicious RT-PCR results, and whose routine laboratory tests were not performed were excluded from the study.

The study was explained in detail to the patients who applied to the COVID-19 clinic of our hospital and met the appropriate criteria for the study. Written consent was obtained from all In previous studies, it was reported that a cut-off value of ≥2 in CURB-65 score has high sensitivity and specificity for demonstrating clinical severity and prognosis of COVID-19 patients [11, 12] . In the present study, the CURB-65 score was used as the clinical severity score. Patients were divided into two groups as CURB-65 <2 (low risk) and CURB-65 ≥2 (high risk) [11] .

A 12-lead surface ECG was performed for all patients with a paper velocity of 25 mm/s and an amplitude of 10 mm/mV. All ECGs were transferred to the digital platform and measurements were made under magnification to reduce calculation errors. ECG records were analyzed by two independent experienced cardiologists. QRS time was calculated from the beginning until the end of the QRS complex, and the QT interval was measured from the beginning of the QRS complex to the end of the T wave. The corrected QT interval (QTc) was calculated according to Bazett's formula: QTc = QT / √RR. Frontal QRS-T angle was obtained from automated reports of ECG recordings.

Statistical Program for Social Sciences 20 (IBM SPSS, Chicago, IL, USA) was used for all statistical calculations. Kolmogorov-Smirnov test was used to check whether the data were normally distributed. Continuous variables were expressed as mean ± SD or median J o u r n a l P r e -p r o o f (interquartile range) and compared with Student's t or Mann-Whitney U tests according to normality. Categorical variables were expressed as percentages and numbers and compared with the Chi-square test. Univariate regression analysis was performed to identify possible risk factors affecting prognosis. In addition, multivariate linear regression analysis was performed to identify independent predictors of prognosis. Receiver operating characteristic (ROC) curve analysis was used to determine the optimum threshold value of frontal (QRS-T) angle level for predicting prognosis in patients with COVID-19. p < 0.05 was accepted as statistically significant in all analyses.

A total of 130 patients (72 women, mean age: 53.44±12.38) and 100 healthy controls (62 women, mean age 51.39±12.70 years) were included in the study. When the comorbid factors of the patients were examined, it was found that 10% of the patients had DM, 9.23% had chronic respiratory disease, and 9.23% had heart failure. 15.38% of the patients were smokers. When the patients were evaluated according to their admission symptoms, 61.54% had shortness of breath, 45.38% had myalgia fatigue, and 41.54% had cough. 55.38% of the patients had a Curb-65 score of '0-1'. 21.53% of the patients were treated in the intensive care unit and 12.30% died. Demographic data and basic clinical characteristics of the patients are shown in Table. 1.

When the patient and control groups were compared a significant difference was found between systolic blood pressure (SBP) ( J o u r n a l P r e -p r o o f Journal Pre-proof 22 .72±14.08, p<0.001) . The comparison of patient and control groups in terms of vital signs, basic laboratory findings and ECG parameters is shown in Table 2 . (Figure 1 ).

In this study, we investigated the ECG changes and the effect of the frontal QRS-T angle on disease severity and prognosis in COVID-19 patients. We found that QT, QTc and frontal QRS-T angle values increased significantly in COVID-19 patients compared to the control group. We also showed that QT, QTc and frontal QRS -T angle values increased significantly as the severity of the disease increased. We also found that frontal QRS-T angle is an independent predictor of disease severity and prognosis. To the best of our knowledge, this is the first study to investigate the effect of frontal QRS-T angle on clinical severity and prognosis in COVID-19 patients.

Previous studies [13] [14] [15] [16] [17] [18] reported that CRP, WBC, glucose, urea, and creatinine values increase in COVID-19 patients and are associated with clinical worsening and prognosis. In addition, it was found that the severity of the disease increases and the prognosis worsens as age and SBP increase. In the present study, it was determined that CRP, WBC, glucose, urea and creatinine values increased significantly in the patient group compared to the control group, consistent with the literature. In addition, an increase in disease severity and worsening in prognosis were detected as age increased. We also showed that age is an independent predictor of disease severity.

Although majority of the focus is on the respiratory system in COVID-19 patients, many cardiovascular system complications of this disease have been reported. In addition, previous J o u r n a l P r e -p r o o f studies reported that prognosis is worse in COVID-19 patients with cardiac involvement [4,6-8]. It is inevitable to see ECG abnormalities in these patients with so many cardiac effects.

QT interval is known as the indicator of myocardial repolarization. Since this range is dependent on heart rate, it is usually measured and reported as the corrected QT interval (QTc). Previous studies reported that prolonged QT is associated with ventricular arrhythmias and cardiovascular mortality [19] . It was also reported that QRS time and QT/QTc are increased in COVID-19 patients [20] [21] [22] . In the present study, we found that QT/QTc and QRS time increased significantly in the patient group compared to the control group. We also showed that the QT/QTc value increased in correlation with clinical severity.

Calculation of QT and QTc parameters is difficult as it requires additional tools, including a magnifying glass and/or computer programs. In addition, the reproducibility of these parameters is difficult and they are affected by heart rate. Therefore, researchers focused on new parameters that can be easily measured by surface ECG [8,10,23]. Frontal QRS-T angle is defined as the angle between the QRS wave showing ventricular depolarization and the T wave showing ventricular repolarization. This value is defined as a new marker showing ventricular depolarization heterogeneity. In addition, it can be easily measured by subtracting the T wave value from the QRS wave value on the surface ECG. 12-lead ECG devices usually calculate QRS and T wave values automatically [23, 24] . In previous publications, it has been reported that the QRS-T angle value is stronger, renewable and less affected by external factors than the QT/QTc value in demonstrating ventricular repolarization [10, 23, 24] . It has also been reported that the frontal QRS-T angle indicates cardiac risk in patients with myocardial infarction and is a predictor of arrhythmic events in patients with decreased left ventricular function [23, 25] . To the best of our knowledge, this is the first study to investigate frontal QRS-T angle and its effects on clinical severity and prognosis in COVID-19 patients.

In the present study, it was found that the frontal QRS-T angle is an independent predictor of J o u r n a l P r e -p r o o f clinical severity and prognosis in COVID-19 patients. Moreover, we showed that a cut-off value of ≥ 44.5° for frontal QRS-T angle had 84.2% sensitivity and 93.8% specificity for predicting mortality. Findings of the present study suggest that introduce frontal QRS-T angle to the literature as a new and powerful predictor in determining clinical severity and prognosis in COVID-19 patients.

There are certain limitations of this study. The study was designed as a single-center study and the number of patients was limited. Investigation of the relationship between frontal QRS-T angle, cardiac injury markers and cardiac arrhythmia in COVID-19 patients may have contributed to our study. Our findings should be supported by multicenter studies with more patients.

The findings of the present study showed that frontal QRS-T angle can be used as a reproducible, convenient, inexpensive, new and powerful predictor in determining the clinical severity and prognosis of COVID-19 patients. 

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