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Year : 2022  |  Volume : 25  |  Issue : 4  |  Page : 415-424

Electrocardiographic QRS axis shift, rotation and COVİD-19

Department of Cardiology, İnfectious Disease, Unıversity of Health Sciences, Keçiören Education and Training Hospital, Ankara, Turkey

Date of Submission09-Jan-2021
Date of Acceptance31-Jan-2022
Date of Web Publication19-Apr-2022

Correspondence Address:
Dr. S Koc
Unıversity of Health Sciences, Keçiören Education and Training Hospital, Ankara
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/njcp.njcp_9_21

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Background: In patients with coronavirus disease-2019 (COVID-19), severe dyspnea is the most dramatic complication. Severe respiratory difficulties may include electrocardiographic frontal QRS axis rightward shift (Rws) and clockwise rotation (Cwr). Aim: This study investigated the predictability of advanced lung tomography findings with QRS axis shift and rotation. Patients and Methods: This was a retrospective analysis of 160 patients. Patients were divided into the following two groups: normal (n = 80) and low (n = 80) oxygen saturation. These groups were further divided into four groups according to the rightward and leftward axis shift (Lws) on the electrocardiographic follow-up findings. These groups were compared in terms of electrocardiographic rotation (Cwr, counterclockwise rotation, or normal transition), tomographic stage (CO-RADS5(advanced)/CO-RADS1–4), electrocardiographic intervals, and laboratory findings. Results: In patients with low oxygen saturation, the amount of QRS axis shift, Cwr, and tomographic stage were significantly higher in the Rws group than in the Lws group. There were no differences in the above parameters between the Rws and Lws groups in patients with normal oxygen saturation. Logistic regression analysis revealed that the presence of Cwr and Rws independently increased the risk of CO-RADS5 by 18.9 and 4.6 fold, respectively, in patients with low oxygen saturation. Conclusion: In COVID-19 patients who have dyspnea with low oxygen saturation, electrocardiographically clockwise rotation with a rightward axis shift demonstrated good sensitivity (80% [0.657–0.943]) and specificity (80% [0.552–>1]) for predicting advanced lung tomographic findings.
ClinicalTrialsgov Identifier: NCT04698083.

Keywords: Clockwise rotation, CO-RADS, Counterclockwise rotation, Covid-19, QRS axis shift

How to cite this article:
Koc S, Bozkaya V O, Yikilgan A B. Electrocardiographic QRS axis shift, rotation and COVİD-19. Niger J Clin Pract 2022;25:415-24

How to cite this URL:
Koc S, Bozkaya V O, Yikilgan A B. Electrocardiographic QRS axis shift, rotation and COVİD-19. Niger J Clin Pract [serial online] 2022 [cited 2022 May 22];25:415-24. Available from:

   Introduction Top

Coronavirus disease-2019 (COVID-19), which is caused by the SARS-CoV-2 virus, started in China in December 2019. COVID-19 has caused a pandemic, and to date, 4.97 million COVID-19-related deaths have been reported.[1] The first stage of COVID-19 occurs in the first 7 days with upper respiratory tract symptoms. Eighty percent of infected patients recover. However, a second or moderate episode of pneumonia occurs in approximately 15% of patients, while about 5% progress to the third phase, which includes severe pneumonia with hypoxemia.[2]

The lung is the most seriously damaged organ in patients with COVID-19. In patients with advanced lung involvement, the alveoli are filled with fluid, white blood cells, mucus, and damaged lung cell debris.[3] Systemic inflammation, direct cardiomyocyte damage, immune response, and hypoxia are among the mechanisms responsible for extensive myocardial damage.[4]

The electrical position of the heart in the frontal plane is defined as normal, right, left, or northwest quadrant axis deviation, while its position in the horizontal plane is defined as clockwise rotation (Cwr), normal transition, or counterclockwise rotation (Ccwr). In Cwr, the transition zone moves towards V5–6, while in Ccwr, the transition zone moves towards V1–2.[5] The change in cardiac configuration is primarily a function of myocardial mass and end-diastolic blood volume.[6] As respiratory disease progresses, rightward shift (Rws) of the frontal QRS axis can result from Cwr of the heart around its longitudinal axis as viewed from the apex, sudden increase in pulmonary vascular resistance causing right ventricle dilatation, or both.[5],[7]

The most striking complaint in patients with COVID-19 is severe dyspnea. Acute respiratory distress syndrome (mean onset time, 8–12 days) develops in approximately one third of affected patients after hospital admission.[8],[9] In hospitalized patients, electrocardiographic changes should be monitored intermittently because this disease progresses rapidly to near 50% mortality within 7–28 days.[10]

A chest computed tomography (CT) scan is an important method to use when diagnosing COVID-19 pneumonia. The large number of patients, limited accessibility, and an absence of professional radiologists can create difficulties.[11] When following-up the progression of lung involvement, a simple and useful method may be needed because sequential CT follow-ups may not be suitable due to an increased radiation risk (i.e., a chest X-ray delivers 0.1 mSv, while a chest CT delivers 2–7 mSv, which is 20–70 times higher than an X-ray) and for economic reasons (i.e., an average of US$500 in the USA and US$250 in South Africa).[12],[13] The aim of this study was to investigate whether easily detectable electrocardiographic axis and rotation changes could predict advanced lung involvement.

   Methods Top

Study design

Records of 250 hospitalized patients with dyspnea and COVID-19 were analyzed retrospectively. COVID-19 patients have been hospitalized in eight different clinics under the supervision of an infectious disease specialist. COVID-19 had not been categorized as a variant of concern, or a variant under investigation. The study duration was 6 months.

Patients were excluded if they received positive pressurized oxygen therapy (n = 25), underwent mechanical ventilation (n =15), exhibited atrial fibrillation (n = 10), conditions precluding the assessment of QRS transitional rotation; complete bundle branch block (n = 10), significant arrhythmias (n = 5, complete atrioventricular block (n = 2), polymorphic ventricular tachycardia (n = 2), and ventricular fibrillation), Wolff–Parkinson–White syndrome (n = 1), supraventricular tachycardia (n = 4), or had unclear QRS axis orientation (n = 20). The remaining160 patients who had electronic medical records, nursing records, at least three electrocardiographic recordings taken a few days apart, and laboratory and tomographic findings were included in the study.

Patients were divided into the following two groups: normal oxygen saturation group (SpO2; ≥90%) who did not receive oxygen therapy (NS, n = 80) and patients with low SpO2 (<90%) who received nasal oxygen therapy (LS, n = 80).

Electrocardiographic (ECG) evaluation

ECG recordings were obtained using an Edan SE-601A 6-Channel ECG Machine, San Diego, USA. Electrocardiographic measurements were performed as previously described. The Tpe (T peak to T end) interval was measured from precordial leads.[14] The delta corrected QT interval (QTc) calculated as last electrocardiographic QTc minus first electrocardiographic QTc. Discrepancies between computerized electrocardiographic analysis and the mean of three computer-aided measurements (Adobe Photoshop program-300dpi resolution) by a researcher were resolved by consultation with a second researcher. The intraclass correlation coefficient was 0.90 (0.85–0.94).

The mean ECG follow-up results were a median of three (range, 3–5) in patients with normal oxygen saturation and a median of five (range, 3–10) in patients with low oxygen saturation.

Using follow-up electrocardiography, according to the direction of QRS axis shift between the first and last electrocardiograms, both groups were divided into two main subgroups: patients with Rws and patients with leftward shift (Lws) of the QRS axis. The patient numbers were as follows: NS Rws (n = 37), NS Lws (n = 43), LS Rws (n = 40), and LS Lws (n = 40).

Based on electrocardiographic follow-up analyses, the two main groups were compared in terms of rotation condition (i.e., Cwr, normal transition, or CCwr), electrocardiographic intervals, and laboratory findings. The transitional zone (those with neither 9-4-1 nor 9-4-2, dominant V3S and V4R), Cwr (MC 9-4-2), and CCwr (MC9-4-1) were evaluated using established Minnesota codes (MC).[14],[15],[16] Axis shift, rotation, and axis shift graphics are shown in [Figure 1].
Figure 1: Top row: Rightward axis shift (Rws), leftward axis shift (Lws). Axis shift rates in patients with low oxygen saturation (first figure) and normal oxygen saturation (second figure). Blue = Rws, orange = Lws. Bottom row: Rotation groups. Septal angle (α) between interventricular septum and horizontal body axis revealed significant differences among rotation groups. NT = normal transition, Ccwr = counterclockwise rotation, Cwr = clockwise rotation, Rv = right ventricle, Lv = left ventricle, top electrocardiogram = Ccwr, bottom electrocardiogram = Cwr

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Tomographic imaging evaluation

Chest CT images were obtained using a Toshiba Aquilion CX 64 Slice CT. Irvine, Canon, USA. Tomographic findings were evaluated in accordance with COVID-19 Reporting and Data System (CO-RADS) classification. CO-RADS scores are as follows: 1 (very low level of suspicion), 2 (low level of suspicion), 3 (equivocal), 4 (high level of suspicion), and 5 (very high level of suspicion).[17] In our study, CO-RADS5 was considered an advanced tomographic finding (e.g., multifocal ground-glass opacities with consolidation, vascular thickening, crazy paving pattern, mixed pattern), while CO-RADS1, 2, 3, and 4 were considered non-advanced tomographic findings.

All patients received the recommended doses of hydroxychloroquine, favipiravir and low molecular weight heparin. Sixteen (20%) of the patients with low saturation had received corticosteroid therapy.

The study was conducted in accordance with the Declaration of Helsinki. This study was conducted with the approval of the Ministry of Health and the local ethics committee.

Statistical analysis

Data analysis was performed using IBM SPSS Statistics version 17.0 software (IBM Corporation, Armonk, NY, USA). Whether the distributions of continuous variables were normally or not being determined Kolmogorov-Smirnov test. The assumption of homogeneity of variances was examined Levene test. Categorical data were expressed as numbers (n) and percentage (%) while quantitative data were given as mean ± SD and median (25th - 75th) percentile. In all 2 x 2 contingency tables to compare categorical variables; the Continuity corrected Chi-square test was used when one or more of the cells had an expected frequency of 5–25, otherwise the Fisher's exact test was used when one or more of the cells had an expected frequency of 5 or less. Unless otherwise stated, Pearson's Chi-square test was used in the analysis of categorical data. While the mean differences between groups were compared Student's t test, otherwise the Mann Whitney U test was used to make comparisons of the continuous variables which the parametrical test assumptions were not met. Diagnostic performance indicators (i.e., sensitivity, specificity, positive and negative predicted values) and 95% CIs for clockwise rotation in order to discriminate the cases with advance CO-RADS and non-advance CO-RADS from each other was also calculated. Multiple logistic regression analysis via Forward LR procedure was performed in order to investigate the best predictor(s) which affect on advance CO-RADS. Any variable whose univariable test had a P < 0.10 was accepted as a candidate for the multivariable model along with all variables of known clinical importance. Odds ratios and 95% confidence intervals for each independent variable were also calculated. Unless otherwise stated, P < 0.05 was considered statistically significant. However, for all possible multiple comparisons, the Bonferroni correction was applied for controlling Type I error.

   Results Top

There were 160 patients in this study (92 men, 68 women; median age, 62 years; range, 53–68 years). The mean body mass index was 29 kg/m2 (range, 27–31 kg/m2). Comorbid conditions included diabetes mellitus in 39 patients (24%), hypertension in 51 patients (31%), and heart failure in 30 patients (18%). Fourteen patients had coronary artery disease as the cause of heart failure.

Other complaints except dyspnea were fever in 85% of the patients, weakness in 90%, cough in 80%, headache in 72%, sore throat in 80%, joint pain in 75%, gastrointestinal symptoms in 30%, and loss of taste and smell in 15%.

All patient groups

In the overall patient cohort, the distribution of tomographic findings was as follows: CO-RADS1–4 in 110 patients (68.7%) (CO-RADS1 in 47 patients [42.7%], CO-RADS2 in 33 patients [30%], CO-RADS3 in 13 patients [11.8%], and CO-RADS4 in 17 patients [15.4%]), and CO-RADS5 in 50 patients (31.2%).

In the overall patient cohort, the overall clinical and laboratory findings were SpO2 = 89% (83–95%), fever = 37°(37–37.8°C), respiratory rate = 20 (20–22) breaths/min, pulse = 88 (74-96) beats/min, systolic blood pressure = 120 (110–130 mmHg), diastolic blood pressure = 75 (70–80) mmHg, high-sensitivity troponin = 47 (14–867) ng/mL, hemoglobin = 11.3 ± 1.91 g/dL, d-dimer = 1250 (905–1867) ng/mL, C-reactive protein = 68 (51–83) mg/L, creatinine = 1.2 (0.9–1.3) mg/dL, alanine aminotransferase = 45 (28–100) IU/L, and glucose = 125 (111–180) mg/dL.

Electrocardiographic intervals were PR= 158(145–170)ms, QRS = 94 (86–104) ms, QTc=414 (400–429 ms, delta QTc=10 (-5–24) ms, QT dispersion = 42 (40–44)ms, Tpe = 82 (80–84) ms, Tpe/QTc = 0.2000 (0.1902–0.2066), mean axis = 20° ± 39, and axis shift = 17 (8–34).

The baseline characteristics of the main two groups are shown in [Table 1].
Table 1: Comparison of baseline electrocardiographic and laboratory characteristics according to QRS axis shift in the overall patient cohort

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Normal and low saturation groups

In the electrocardiographic analysis, the amount of axis shift [[Figure 1], top row] and the Tpe time were statistically significantly higher and the mean axis was lower in the LS group compared to the NS group.

Platelet count, alkaline phosphatase level, and fibrinogen level did not significantly differ between groups. In patients with LS, there was reduction in hemoglobin compared with patients with NS. There were enhancements in glucose, creatinine, high-sensitivity troponin, C-reactive protein, and d-dimer levels.

Comparison of the Rws and Lws groups in patients with NS revealed differences in diastolic blood pressure, pulse, and Tpe. There were no differences in laboratory values between (two) the Rws and Lws groups in patients with NS. However, there were differences in some biochemical parameters in the LS group, as shown in [Table 2].
Table 2: Comparison of characteristics among low oxygen saturation subgroups

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Rotation and axis shift rates

In the overall patient cohort, while there was no difference in the mean axis, differences could be found in the QRS axis shift between the Rws and Lws groups. The Cwr rate and CO-RADS5(cases that had 16% (n = 8) less than 50% involvement, 84% (n = 42) greater than 50% involvement)/CO-RADS1–4 ratio were significantly higher in the Rws group than in the Lws group.

In patients with low oxygen saturation, the axis shift, Cwr rate, and CO-RADS5-to CO-RADS1–4 ratio were significantly higher in the Rws group than in the Lws group. There was no difference in the NS group for these parameters. [Table 3] shows the mean axis, axis change, rotation, and CO-RADS data for patients in all groups.
Table 3: Comparison of mean axes, axes changes, rotation, and CO - RADS rates in the overall patient cohort, as well as in patients with normal and low oxygen saturation

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Diagnostic performance and regression analysis

Diagnostic performance analysis was used to determine the ability of Cwr to predict CO-RADS5 in all patient groups. In the NS group, sensitivity was 37.5% and specificity was 75%. Other results are shown in [Table 4]. In the NS group, the Cwr and QRS axis shift alone had no effect on CO-RADS5 detection. The effects of the Cwr and QRS axis shift on CORADS 5 detectability are shown in [Table 5].
Table 4: Diagnostic performance of clockwise rotation for the prediction of CO - RADS 5

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Table 5: The results of multiple logistic regression analysis determining the best predictors which discirimante the cases with advance CO - RADS from non - advance CO - RADS each other

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   Discussion Top

Our study showed that concurrent electrocardiographic Rws and Cwr could predict advanced tomographic findings with 80% sensitivity and 80% specificity in patients with COVID-19 who had low oxygen saturation. In patients with low oxygen saturation, QRS axis shift was significantly higher in the Rws group than in the Lws group.

Ventricular (QRS) axis

A QRS axis shift of >40° is a strong, independent predictor for ventricular tachycardia,[18] independent of QRS duration.[19] Concurrent Cwr and Rws can also be detected in patients with pneumothorax[20] and have demonstrated sensitivity for the detection of left ventricle capture in resynchronization.[21]

In an analysis of exercise stress test records involving 1810 patients, Rws or Lws ≥30° were associated with 15.8% and 33.3% rates of test positivity, respectively, while clinical ischemic coronary artery disease rates were 26.3% and 50%, respectively. For patients ≤15°axis shift, coronary artery disease rates were 6.5% and 8.5%, respectively.[22] In our study, which had a smaller number of patients with LS, rates of heart failure (11/13) and underlying coronary artery disease (4/4) were similar between the Rws and Lws groups.

Frontal QRS axis shift to the left causes a QRS loop with longitudinal Ccwr. Because an approximately 3°change in frontal QRS axis can create a 1° change in heart position, an approximately 12° change in frontal heart position is suspected in the Rws group among patients with LS. Furthermore, exhalation-created Cwr through the diaphragm and cardiac frontal elevation[23] may have affected the rotation rates in this group.

Clockwise and counterclockwise rotation

Approximately two thirds of Cwr and CCwr can be explained by tomographic anatomical rotation of the heart in a single plane around the long axis. Cwr primarily occurs in right ventricular heart disease when the enlarged right ventricle exerts pressure on the left ventricle. Dilated cardiomyopathy also may create Cwr by causing posterolateral displacement related to conduction abnormalities or an enlarged heart.[6],[24] In 16 (66%) of 24 patients with heart failure in the LS group and 18 (55%) of 33 patients with Cwr in the LS group, non-contrast imaging tomography showed that the right ventricle was >42 mm wide at the basal level.

In patients with mild tomography findings that do not involve right ventricular loading, Cwr can be detected electrocardiographically. These patients may have pre-existing right ventricular hypertrophy, type A Wolff–Parkinson–White syndrome, posterior myocardial infarction.[24] There were four such patients in our study. These patients had a history of smoking.

Viral infections cause ischemic stress in the heart. Systemic diseases, hypoxia, and biochemical changes may influence these effects.[25] In general, right ventricle strain will create Rws, whereas left ventricle strain will create Lws.[26] In the Rws group, systolic and diastolic blood pressures were lower, QTdispersion and Tpe were longer, and Tpe/QTc ratio and high-sensitivity troponin level were higher, compared with the Lws group [Table 1]. These findings suggest that the right-sided myocardium is more likely to be affected. The presence of differences in aspartate and alanine aminotransferases, as well as the absence of differences in gamma-glutamyl transferase and alkaline phosphatase [Table 2], suggest that, in patients with LS, the Rws group is more affected by low cardiac output compared with the Lws group.[27]

Left ventricular rotation greatly enhances intracavitary pressures and stroke volume in systole, minimizing the oxygen demand of the myocardium. In our study, there was a significant difference in pulse between patients with NS and patients with LS. Tachycardia is a typical sign of infection that increases the rotational deformation of the left ventricle and ensures consistent stroke volume.[28]

Left ventricular rotation was observed in the Cwr direction in patients with hypertension or diabetes mellitus.[29],[30] Yasuyuki and Siddharth[15],[31] found that Cwr was significantly positively associated with heart failure in large cohorts (n = 9067 and n = 13,567, respectively). Those authors concluded that the repeatability of Cwr was a sufficient electrocardiographic finding for predicting cardiovascular disease mortality. Cwr also confers increased risks of all-cause mortality and cardiovascular disease-related mortality in patients without cardiovascular disease.[16] Hypertension, diabetes mellitus, and heart failure were present in 25%, 13,7%, and 7.6% of patients with NS; in 38,7%, 35%, and 30% of patients with LS; 39%, 51%, and 33% of patients with LS in the Cwr group.

Positive pressurized oxygen therapy and mechanical ventilation have complex effects on lung and right ventricular dynamics. Patients receiving these interventions were not included in the study because they may exhibit continuous axis shift.[32] There is a potential for respiratory dyspnea in patients with CO-RADS5. Acute respiratory distress syndrome has also been defined as right ventricular afterload disease caused by ventriculo-arterial uncoupling that results from increased pulmonary vascular resistance.[33],[34] The differences in nearly all laboratory parameters between patients with NS and patients with LS suggests a close association between respiratory and systemic effects. In subsequent follow-up, six of our patients with LS (three with Cwr, two with Ccwr, and one with normal transition) had signs of acute respiratory distress syndrome.

Electrocardiographic other changes

In one study, more ECG abnormalities were detected in Covid-19 patients hospitalized in the intensive care unit.[35] Other electrocardiographic abnormalities were detected as Q-wave abnormalities (MC 1-3, n = 12), ST-T abnormalities (MC 4-1 to 4-4, n = 15), T-wave abnormality (MC 5-1 to 5-4, n = 18), prolonged QRS duration (n = 19), sinus bradycardia (MC 8-8, n = 11), sinus tachycardia (MC 8-7, n = 12), first-degree atrioventricular block (MC 6-2, n = 12), ventricular premature systole (MC 8-1-2, n = 15).

The reproducibility of QRS axis deviation is good[36] while computerized electrocardiographic analysis is reliable and superior to visual reading.[37] We used both of these analyses in the present study. The Tpe interval (measured from precordial leads) and Tpe/QTc ratio (unaffected by heart rate) are also used for the possibility of ventricular arrhythmia, which is considered an indicator for ventricular repolarization and dispersion increase.[38],[39] Prolongation of Tpe could be a new predictor of adverse outcomes in pulmonary arterial hypertension.[40] There was a difference in Tpe between patients with NS and patients with LS. Although this suggests that repolarization of the epicardium and myocardium may be affected in patients with LS, our number of patients was insufficient to make robust conclusions.

The axis shift, clockwise rotation, and CO-RADS5 rates were statistically significantly higher in the LS group compared to the NS group when there was both low oxygen saturation and a rightward axis shift. Therefore, this LS group may be at greater risk of worse respiratory system-related findings. There was no difference in the NS group in terms of the above parameters. An example of the association between clockwise rotation and CO-RADS5 is shown in [Figure 2].
Figure 2: Representative relationship between clockwise rotation and CO-RADS 5

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Relatively higher positions of precordial electrocardiographic leads may have affected our results.[24] The electrical axis was not correlated with the anatomic cardiac axis (mean cardiac axis: 38.1°±7.8° on computed tomography, versus electrical cardiac axis on electrocardiography: 51.8° ± 26.6°).[41] Failure to perform follow-up electrocardiography and tomography might have also affected the results, as lesions may progress up to 10 days.[42] Due to the number of patients, regression analysis found wide confidence intervals for Cw rotation in patients with LS. At the end of the research period, the indication for corticosteroid therapy has expanded.[43] The possible effect could not be studied in our study. This study should be performed in a larger patient cohort for more conclusive findings.

   Conclusions Top

In patients with COVID-19 who exhibit dyspnea with low oxygen saturation, clockwise rotation with a rightward shift showed good sensitivity (80%[0.657–0.943]) and specificity (80%[0.552–>1]) for detecting advanced tomographic findings.

Author contributions

Şahbender Koç: Conceptualization, Software, Data collection and curation, Formal analysis, Resources, Writing original draft. Veciha Özlem Bozkaya: Methodology, Writing and Revision. Aslıhan Burcu Yıkılgan: Revision, Validation.


The authors are grateful for radiology support provided by radiologists.

The authors declare no conflicts of interest.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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