IV. DISCUSSION

ELECTROCARDIOGRAM FINDINGS OF COVID-19 PATIENTS

In the initial ECG, majority of patients had already prolonged QT, followed by ischemic changes and fascicular blocks. A great number of patients developed abnormalities
in succeeding ECGs with development of new QT prolongation, further prolongation in QT from baseline, ischemic changes and fascicular blocks. Most of mortality [90.91%]
in our study had ECG abnormalities namely QT prolongation, ischemic changes, fascicular blocks, bundle branch blocks and one ECG showing Brugada pattern.

In the study by McCullough et. al, they performed a retrospective cohort study in patients with COVID-19 who had an ECG at or near hospital admission. Clinical characteristics and ECG variables were obtained from the health record and first ECG where the primary outcome was death. Presence of atrial premature contractions (APCs), repolarization abnormalities, a right bundle branch block (RBBB) or intraventricular block and ischemic T wave changes increased the odds of death. This study was able to explain the probable cause of Right Bundle Branch blocks which could be attributed to acute right ventricular overload and distention in pulmonary embolism.¹⁰ The said ECG changes were also seen in our study present during baseline ECG and even developing during the course of admission. However, this was also observed among survivors.

What is striking in this study is the presence of QT prolongation during their first recorded ECG and even worsening of QT prolongation in majority of the patients during the course of admission. It should be taken into consideration that this initial ECG may already reflect some degree of treatment. This finding could be attributed to the use of antimalarials and antivirals that is used in the treatment of this disease. In the study of Mercuco et. al. and Chorin et. al., patients who received hydroxychloroquine for the treatment of COVID-19 were at high risk of QTc prolongation, and concurrent treatment with azithromycin was associated with greater changes in QTc^{11, 12} with one patient developing Torsades de Pointes requiring cardioversion.¹²

One patient included in the study was noted to have Brugada pattern on ECG which was not present during admission. Chang et. al. presented a case of a COVID-19 infection unmasking Brugada syndrome. COVID-19 infection is typified by fever, a known precipitant of arrhythmia in patients with Brugada syndrome. Uncontrolled fever in patients with Brugada syndrome portends higher risk for syncope and sudden cardiac arrest.³ The increase in the body temperature has been proven to cause a higher degree of inactivation of Na+ channels. This reduced Na+ flow can result into a dangerous transmural heterogeneity which is the basis for phase 2 reentry ventricular arrhythmias and sudden death.¹³ Patient with this finding may warrant more aggressive antipyretic therapy.

ECHOCARDIOGRAPHY FINDINGS OF COVID-19 PATIENTS

Findings in our study showed that left ventricular systolic function are preserved in majority of the patients. Results of right ventricular function were also mostly normal even among patients in whom ARDS was identified (only one patient had an abnormal RVFAC). Even though difference was observed in the TAPSE between critical and non-critical patients, results are still both normal. In the present literatures reviewed, inconsistent data with regards to abnormalities in 2D echo were found. Findings could be normal, predominance of right ventricular dysfunction, predominance of left ventricular dysfunction or both.

In a study done by Szekely et. al., it was seen that among patients with abnormal echocardiogram at presentation, systolic left ventricular dysfunction was uncommon, observed in less than 10%. The most frequent abnormality was RV dilation with or without dysfunction, possibly related to pulmonary parenchymal or vascular disease.¹⁴ Another study by Sud et. al. showed regional LV dysfunction appears to be the most common echocardiographic finding, suggesting that ischemia due to large- or small-vessel obstruction and prothrombotic state may be a common mechanism of injury.¹⁵

The reported results of Dweck, M. et al. was the first international survey of echocardiography in patients with confirmed or suspected COVID-19. Patient undergoing echocardiography had clearly defined clinical indications of performing such evaluation (i.e. suspected left or right sided heart failure, chest pain with ST segment elevation on the electrocardiogram, cardiac biomarker elevation [troponin or brain natriuretic peptide (BNP)], ventricular arrhythmia, suspected tamponade or cardiogenic shock). This study demonstrated left or right ventricular abnormalities in half of all patients with COVID-19 undergoing echocardiography, and that these abnormalities were severe in 1 of 7 patients. The majority had non-specific patterns of ventricular dysfunction, although new myocardial infarction, myocarditis, and takotsubo cardiomyopathy were observed in a minority of patients. Echocardiography was reported to directly change patient management in a third of cases including alterations to disease specific management, hemodynamic support, and the level of care received by the patients.¹⁶

Furthermore, almost all patients who died had abnormal ECGs. Only one mortality had an abnormal echocardiography result. Still, no significant difference was noted in both electrocardiogram and echocardiographic findings between survivor and non-survivors. While all mortalities in this study had ARDS and shock, abnormalities in ECG and 2D echo, reflecting cardiac involvement, may not have implications in survival. Death from the said disease could mainly be due to the acute lung injury and the severe inflammatory response thereby secondarily affecting the heart by increasing the cardiac workload. Focusing on improving the ventilation and circulation of patient may probably improve disease outcomes.

One of the limitations of this research is its small sample size. Most patients included in the study had only one 2D echo result. Not all patients had cardiac biomarkers, 12 L ECG and 2D echo because during the data gathering period of this study, there was still evolving knowledge about COVID treatment and the needed ancillaries. It would be better if more data will be reviewed and added to this research with serial examinations of ECG and 2D echo done as baseline and during the varying severity if the illness. Also, future research could investigate correlation of abnormalities in 2D echo with regards to co-morbidities of the
patient.

This study supports the recommendation of ESC to avoid performing routine transthoracic echocardiography in which test results are unlikely to change the management strategy. Moreover, findings regarding the prevalence of QT prolongation should alert physicians on the risk of developing drug-induced torsades de pointes and sudden cardiac death thereby validating the importance of correcting electrolytes and avoiding drugs that could prolong the QT interval if not necessary. A clear indication of why an ECG and echocardiogram is being done could lessen risk exposure of health care workers, conserve personal protective equipment, and appropriately allocate resources of our patients.