The respiratory failure syndrome caused by SARS-CoV-2 began in the city of Wuhan, China, in December 2019 and was officially declared a pandemic by the World Health Organization (WHO) on March 11, 2020.¹ It has similarities with viruses such as SARS-CoV and MERS-CoV, responsible for previous pandemics, but with specific characteristics demonstrated over the years of the pandemic.^2,3

The viral structure is composed of a single-stranded RNA molecule with positive polarity, surrounded by a lipid bilayer where the S protein, membrane (M), and envelope (E) are anchored, responsible for the infection and cellular multiplication of the virus. The main clinical manifestations are cough, fever, dyspnea, and loss of taste and smell, observed in different populations worldwide. In this context, the impact of the COVID-19 pandemic on patients with cardiovascular disease has been significant, despite many of these individuals having multiple comorbidities.^4,5

This fact was reinforced when the first cases of COVID-19 infection were described in the literature, where the most severe cases with comorbidities such as coronary artery disease (CAD), systemic arterial hypertension (SAH), and diabetes mellitus (DM) were associated with worse clinical outcomes, such as the need for intensive care unit (ICU) admission and mortality.⁶

This study aimed to assess the impact of COVID-19 infection on quality of life in patients with prior coronary artery bypass graft surgery (CABG).

A total of 434 patients undergoing isolated CABG were included, with a mean age of 63 years and male prevalence of 71%. The main comorbidities identified were hypertension (85%), dyslipidemia (61%), DM (53%), and prior acute myocardial infarction (AMI) (53%). Out of the initial cohort, 115 completed the 4-year follow-up, during which they were contacted by telephone to complete the quality of life questionnaire. Among these, 60 patients were confirmed to have COVID-19 based on WHO criteria. The demographic characteristics are shown in Table 1.

Table 1

Variables	N = 434
Age, mean (SD)	63 (9)
Gender, n/N(%)
Male	309/434 (71%)
Height, mean (SD)	165 (9)
Weight, mean (SD)	77 (15)
BMI, mean (SD)	28.0 (4.4)
SAH, n/N(%)	371/434 (85%)
Dyslipidemia, n/N(%)	265/434 (61%)
Chronic obstructive pulmonary disease, n/N(%)	16/434 (3.7%)
Peripheral arterial disease, n/N(%)	22/434 (5.1%)
Chronic kidney disease, n/N(%)	45/434 (10%)
DM, n/N(%)	232/434 (53%)
Stroke, n/N(%)	22/434 (5.1%)
Acute myocardial infarction, n/N(%)	228/434 (53%)
Arrhythmia, n/N(%)	11/434 (2.5%)
Smoker, n/N(%)	241/434 (56%)
COVID test results, n/N(%)
COVID-19 Positive	60/115 (52%)

SAH: systemic arterial hypertension; DM: diabetes mellitus; SD: standard deviations; BMI: body mass index.

In addition to the demographic analysis, the patients’ quality of life was assessed using the QLCS questionnaire, comprising 5 questions: 1) How is the patient's performance in daily activities/work/school?; 2) How is the patient's health after surgery?; 3) How is the patient's physical capacity after surgery?; 4) From an emotional standpoint, how is the patient feeling?; 5) In their relationship with family members, how is the patient feeling? The questionnaire has a maximum score of 25 points and has been validated in previous studies for the analyzing patients undergoing CABG.

A statistical difference was observed between 1 and 4 years for all components of the QLCS questionnaire. Additionally, the comparison of scores over the follow-up period, accompanied by their respective 95% CI and P values, is presented in Table 2, showing a statistically significant difference across all periods.

Table 2

Comparison	Difference	Confidence Interval 95%		P Value
		Inf	Sup
30 days - 6 months	-1.12	-1.52	-0.73	<0.001
30 days - 1 year	-1.83	-2.22	-1.43	<0.001
30 days - 4 years	1.32	0.71	1.92	<0.001
6 months - 1 year	-0.70	-1.10	-0.30	0.0005
6 months - 4 years	2.44	1.84	3.05	<0.001
1 year - 4 years	3.14	2.54	3.75	<0.001

Afterward, we specifically assessed patients diagnosed with COVID-19 during follow-up, according to the WHO definition of confirmed cases. Out of 115 patients, 60 were confirmed cases. The boxplot graphs below (Figure 1) depict the distribution of the quality of life scores in each group, showing that the median score among COVID-19-positive patients is lower compared to those without a history of infection. It is important to note that in the first year of follow-up, therefore a period predating the COVID-19 pandemic, the scores exhibited similar patterns.

Figure 1

QLCS: Quality of Life in Cardiovascular Surgery.

This study reveals that patients with a history of COVID-19 infection experienced worse quality of life scores. The context of the COVID-19 pandemic has impacted several cardiovascular surgery centers worldwide, showcasing a broad spectrum of patient symptoms, discussion on therapies, the emergence of SARS-CoV-2 variants, and the historical progression of vaccines.^1,3,9

Understanding the mechanisms of viral infection has been fundamental to understanding the impact of COVID-19 on patients with cardiovascular disease. Chung et al.¹⁰ demonstrated in a review the significance of the angiotensin-converting enzyme 2 (ACE2), which is present in cells of the respiratory system, kidneys, heart, and blood vessels. ACE2 serves as a substrate for binding the SARS-CoV-2 virus via its surface proteins, and subsequently viral replication, enabling the infection of other cells. The organic response to infection relies on the action of the immune system (both innate and adaptive), which, in association with the "cytokine storm," contributes to cell damage and the disease severity, particularly among patients with cardiovascular disease.^10,11

Thakker et al.,¹² in a systematic review of patients diagnosed with acute coronary syndrome both with and without COVID-19, observed higher mortality rates in the former group. This outcome can be attributed to several factors, including pre-existing comorbidities such as SAH, DM, and dyslipidemia, as well as diagnostic delays. Many of these factors were present in the patients included in this study, given the various changes in healthcare amid the pandemic.

When considering the global impact of the COVID-19 pandemic, its effects on the treatment of patients with cardiovascular disease become evident. In England, the number of CABGs decreased by 64%, while in the USA, according to STS data, there was a 52.6% reduction in the volume of heart surgeries. Additionally, in Canada, patients referred for CABG experienced higher mortality rates during the pandemic, with COVID-19 infection identified as a predictor of mortality in several studies.^13-16

In Brazil, Khalil et al.¹⁷ conducted and analysis involving 281,760 CABGs carried out between January 2008 and December 2020, revealing a reduction of around 25% in surgical volume in 2020. This reduction was accompanied by an increase in mortality rates in certain regions of the country, such as the southeast and center-west. Mejia et al.,¹⁸ in an analysis of 650 patients, reported a 62% reduction in CABG volume, highlighting a devastating impact on surgical outcomes in Brazil. The authors noted a higher mortality among the subgroup of patients with COVID-19, as well as an increased incidence of associated complications. In the multivariate analysis, COVID-19 and postoperative pneumonia were identified as markers of post-CABG mortality.

Secondary outcomes such as ICU admission, acute myocardial infarction, and thromboembolic events did not differ statistically in this study. This outcome may be attributed to national public policies observed during follow-up, including a notable prevalence of vaccinated patients, with 100% of the sample having received at least one to two vaccine doses.

The reduction in surgical volume, associated with higher mortality and post-operative complications, directly impacts patients' quality of life. Algahtani et al.,¹⁹ in an analysis of 754 patients, used the WHOQOL-BREF questionnaire to demonstrate that patients with chronic conditions such as hypertension, diabetes, and cardiovascular disease reported worse quality of life scores, findings consistent with those of this study. Al Dhaheri et al.²⁰ investigated the mental health implications for patients during the COVID-19 pandemic, emphasizing on the role of family support.

The impact on the quality of life of patients undergoing CABG is notorious; in our study, for instance, quality of life remained stable during the first year of follow-up in a pre-pandemic context.^21,22 Bond et al.^7,8 demonstrated the improvement in patients' quality of life scores at the 1-year follow-up using the QLCS score. However, the COVID-19 pandemic has brought major challenges in the management of CAD patients undergoing CABG, whose long-term implications are yet to be fully understood.

Huang et al.²³ observed persistent symptoms such as fatigue, anxiety, and depression six months after hospital discharge among patients who had been admitted to an ICU. These findings are supported by other studies, where quality of life, measured by other tools such as the SF-36 score, was reduced in patients with COVID-19.^24,25

Patients with CAD undergoing CABG present multiple comorbidities. Quality of life serves as an important metric for assessing the therapeutic impact of surgery, with different questionnaires currently validated. Discussions concerning socioeconomic factors, public policies, and rehabilitation programs are pertinent in the ongoing treatment of patients dealing with COVID-19 sequelae.^26-28

Furthermore, it is important to note that this study reflects real-life conditions. For reasons inherent to the COVID-19 pandemic experienced in Latin America, such as appointment cancellations and the inability to conduct necessary postoperative tests, follow-up data for all the initially enrolled patients could not be collected, impacting the final 4-year sample. This was a significant limiting factor in this analysis.

In this study, it was observed that patients with prior CABG and a history of COVID-19 infection experienced worse quality of life scores at the 4-year follow-up. However, there was no statistical difference in acute myocardial infarction, stroke, or thromboembolic events between the groups with and without COVID-19. To the best of the authors' knowledge, this is the first study in the literature to assess the impact of COVID-19 infection on the quality of life of patients with prior CABG using the QLCS questionnaire.