European Journal of Cardiovascular Medicine

A major outbreak of pneumonia cases were reported due to “severe acute respiratory syndrome coronavirus 2” (SARS-CoV-2) at the end of 2019 in the city of Wuhan, in the Hubei Province of China. Soon COVID-19 was declared as a pandemic.¹ Initially as a respiratory infection and now known to affect all major organs. Very little is discussed about cardiovascular involvement in COVID. It has been observed that lung involvement is more severe in patients with preexisting cardiac involvement. However, in a few patients and few patients do present with cardiac symptoms alone without lung involvement.² The spectrum being no cardiac disease at all, asymptomatic with elevated cardiac markers, symptoms of overt cardiac disease such as angina, heart failure, cardiac arrhythmias, and sudden cardiac death.

Arrhythmia and acute cardiac injury were reported in 16.7 and 7.2% of the COVID patients.³ In addition to the systemic inflammatory response, the physiological mechanisms identified to cause cardiac involvement are hypoxemia-related myocardial cell injury and endothelial cell damage due to upregulated expression of angiotensin-converting enzyme 2 (ACE 2) in the heart and lungs.⁴

Myocardial ischemia and electrolyte abnormalities were the factors identified to cause arrhythmias.⁵ The presence of cardiac involvement may imply poor prognosis and an adverse outcome.⁶

Therefore, it is necessary to assess and monitor the cardiac abnormalities for a prompt action. ECG, a simple bedside diagnostic test with high prognostic value used to assess cardiovascular involvement in COVID-19 patients.

This cross-sectional, hospital-based prospective study was conducted among 300 COVID-19 patients admitted in our tertiary care center of North Karnataka during April to June 2021 after obtaining the institutional ethics committee clearance and informed consent. Patients whose COVID status was confirmed by real-time reverse transcriptase polymerase chain reaction on nasopharyngeal and oropharyngeal swabs were included in the study.

Consecutive patients admitted to our hospital with SARS-CoV-2-positive status underwent ECG testing on admission and were included in the study. Patients’ clinical profiles that include symptoms, duration, and severity of illness, and comorbid status were noted from their clinical records.

Patients with ventricular pacing, immune suppression, stroke, malignancy and patients on beta blockers and anti-arrhythmic drugs were excluded.

The ECG data included  rate, rhythm categorized as normal sinus rhythm or atrial fibrillation/flutter, atrial premature contractions, ventricular premature contractions, atrioventricular block, axis deviation, bundle branch block, intraventricular conduction block (QRS duration of >110 ms), Bazett-corrected QT interval (in milliseconds), presence of left or right ventricular hypertrophy, myocardial infarction, and the presence of ST segment or T-wave changes (localized ST elevation, localized T-wave inversion, or other nonspecific repolarization abnormalities).

Statistical Analysis

The data collected were tabulated using Microsoft Excel. For analysis Descriptive statistics were employed. Data were expressed as mean ± standard deviation for continuous variables and proportions for categorical variables. Logistic regression analysis was employed to study the association between clinical variables and occurrence of various types of ECG abnormalities. The results were expressed in odds ratio with 95% confidence interval after adjusting for important confounders.

A total of patients satisfying the inclusion criteria were included in the study. Out of the total 300 patients studied, 90 (29.2%) were females and 210 (70.8%) were males with an average age of 52.6 ± 16.3 years. Clinical characteristics like symptoms on admission, severity and duration of illness, duration of the hospital stay, disease course, and outcomes are depicted in Table 1.

Table 1: Demographic and clinical characteristics of the study population

Among the abnormal ECGs 255 (81%), rhythm abnormalities were seen in 9 patients (2.9%); rate abnormalities in 115 patients (36.5%)—bradycardia (12.7%) and tachycardia (23.8%); and prolonged PR interval in 2.9% patients. Short QRS complex was seen in 8.3%. QT interval was prolonged in 8.3% of the patients. There were significant changes in the ST and T segments (Table 2).

Table 2: Distribution of ECG changes at admission among the study population

In logistic regression model (Table 3), subjects with moderate-to-severe COVID-19 illness were twice likely to have at least one of the above-described abnormalities in ECG independent upon age, gender, and preexisting cardiac diseases [adjusted odds ratio 2.02 (95% confidence interval 1.04–3.95)]. Among all subjects, ischemic changes in ECG (ST segment changes and T-wave inversion) appeared to be associated with systemic hypertension [adjusted odds ratio 1.73 (95% confidence interval 0.96–3.11)] and respiratory failure [adjusted odds ratio 1.58 (95% confidence interval 0.94–2.66)] after adjusting age, gender, and preexisting heart diseases. The above-mentioned associations showed a trend toward statistical significance. No other ECG changes had any significant association with clinical variables studied.

Table 3: Logistic regression analysis of association between ECG changes and clinical variables

Of the 315 patients, 19 patients died ultimately due to COVID. The ECG abnormalities studied in these patients. Prolongation of QTc interval (42%) and tachycardia (36.8%) were the commonest changes noted in them. The various ECG abnormalities encountered in the study population and the outcomes in each group are depicted. Adverse final outcomes were noted in 11.5% of the patients who had ST-T changes and QTc prolongation and 8.4% of the patients who had tachycardia.

Myocardial injury has been commonly reported in infectious diseases. ECG changes observed in infections include hemorrhagic fever,⁷ leptospirosis,⁸ scrubtyphus,⁹ diphtheria etc.  Myocardial injury observed in dengue viral infection with ECG abnormalities like atrial and ventricular premature beats, prolonged PR interval, bundle branch block’s, and ST and T segment changes.¹⁰ Abnormal ECG findings were found to be reported in 28% of the hospitalized patients infected with novel H1N1 influenza virus.¹¹ Similarly there is evidence that SARS-CoV-2 also has the potential to have a negative impact on the cardiovascular system.

There are multiple proposed mechanisms for cardiac damage in COVID-19. These include cytokine release syndrome,¹² direct myocardial damage as in viral myocarditis due to the interaction between virus and ACE 2,¹³ coronary spasm, induction of a hypercoagulable state, plaque instability causing rupture, and acute coronary syndrome.¹⁴ Other mechanisms may be included are cardiac toxicity due to antivirals, steroids, and electrolyte abnormalities.

In our study, we observed sinus tachycardia (23.8%), sinus bradycardia (12.7%), and atrial arrhythmia (3.5%). This is in accordance with a study by Brit Long where the commonest ECG abnormality in COVID patients was sinus tachycardia followed by atrial fibrillation, ventricular arrhythmias, QTc prolongation, and ST-T segment changes.¹⁵ Atrial fibrillation (3.5%), bradyarrhythmia (1.2%), and nonsustained VT (10.4%) were reported in another study conducted among 700 patients with severe acute respiratory syndrome due to SARS-CoV-2 infection.¹⁶

In our study, we encountered ischemic changes (ST segment elevation, T-wave inversion) in 32.4% of the COVID-19 patients irrespective of their underlying cardiac health. Italy published a research study of 28 COVID-19 patients who underwent angiogram for ST elevation myocardial infarction in whom 86% had STEMI as the first presentation of COVID showing that acute coronary event had preceded systemic inflammation.¹⁷

In the present study, 16.2% of the COVID-19 patients presented with QT segment changes (prolonged and shortened). QT interval prolongation has been noted in about 13% of the COVID-19 patients. Major contributing factors to this particular abnormality may be the list of several (now unapproved) drugs previously used for COVID-19 treatment like hydroxychloroquine and azithromycin.¹⁸ 

All the 19 COVID patients who had succumbed to death had abnormal ECG findings. In a retrospective study to highlight the prognostic significance of ECG in COVID, Yang et al. have compared the ECG changes in survivors and nonsurvivors. It was observed that the nonsurvivors had significantly higher rates of prolonged QTc interval, axis deviation, arrhythmias, ST-T changes, and an overall higher abnormal ECG score. In our study population, QTc prolongation and tachycardia were the commonest changes in the deceased.

In our study, COVID-19 patients had ECG changes like conduction defects, ischemic changes and rhythm abnormalities. With SARS-CoV-2 having already gained momentum worldwide, it is important to deploy simple, cost-effective bedside examination, and diagnostic tests considering our limited health resources. ECG is of paramount importance in the Emergency COVID Department too as it is central to risk stratification and is predictive of an adverse outcome.

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