Understanding outcomes of emergency aortic dissection repair during COVID‐19 pandemic: What lessons have we learnt?

1.

The COVID‐19 pandemic caused a global strain on healthcare resources and infrastructure in more than 180 countries. This includes the care given to critically ill patients. According to the World Health Organization, there have been over 1,300,000 cases and 80,000 deaths from COVID‐19 as of April, 2020. ¹ To combat these pressures, the American College of Surgeons and the Centres for Medicare and Medicaid Services suggested the deferral of all elective surgical cases in favor of focusing on more urgent presentation. The aim was to reduce the risk of hospital transmission of the virus, as well as the maintenance of vital resources. ² , ³ However, clear guidelines remained unknown regarding the management of life‐threatening conditions, such as Acute Type A Aortic Dissection (ATAAD), in such circumstances, whereby the delay in surgical intervention could have been detrimental to the patient.

Patients undergoing cardiac surgery have a five‐time greater risk of death when concurrently positive for COVID‐19. ⁴ Cardiovascular diseases, such as coronary artery disease, chronic heart failure and congenital heart disease have also been identified as the strongest risk factors for poorer clinical outcomes in patients with COVID‐19. ⁵ In contrast, the risk of developing other cardiovascular conditions, such as acute coronary syndrome and arrhythmias has been shown to increase in those infected with SARS‐CoV‐2. ⁶ Despite this, the incidence of acute aortic emergencies, such as ATAAD was less at the start of the pandemic and acute hospital presentations from acute myocardial infarction were reduced. ¹ , ⁷ Whilst there is an abundance of literature concerning the outcomes of patients with COVID‐19 and cardiovascular conditions, there is limited comparable research available concerning the impact of COVID‐19 on the outcomes of ATAAD, which is equally important to explore. Therefore, this study utilized The Society of Thoracic Surgeons Adult Cardiac Surgery Database (STS ACSD) to evaluate the presentation patterns and outcomes of ATAAD repair in North America. Data was analyzed of patients in the pre‐pandemic and early COVID‐19 pandemic phase.

In this issue of the Journal of Cardiac Surgery, Arnaoutakis ⁸ reported the results from a multi‐center retrospective, observational cohort study collated from the STS ACSD. They found the volume of cases of ATAAD was significantly lower during the COVID‐19 pandemic compared to pre‐pandemic. However, in low volume centers of less than 10 cases of ATAAD generally presented, there was little difference between the two phases, with 140 cases in the pandemic period versus 177 in the prepandemic time. In addition, there was no significant difference in hospital‐to‐hospital transfers, with 54% of transfers prior and 55% during the COVID‐19 pandemic. This study included a combination of patient demographic, operative characteristics, malperfusion rates, and cardiovascular risk factors, which were similar across the two groups. The authors recommend further studies on out‐of‐hospital mortality to guide management of ATAAD during future public health outbreaks. This was based upon operative mortality (in‐hospital death or death within 30 days of surgery) or morbidity showing no difference between prepandemic and during in this study, whereby out‐of‐hospital mortality is scarcely cited in the current literature.

Furthermore, clinical guidelines for the management of ATAAD repair in COVID‐19 are deficient compared to other cardiovascular conditions. This is due in part to the limited literature available on the outcomes of ATAAD in COVID‐19. For example, SARS‐CoV‐2 infection has shown to exacerbate arrhythmias, acute coronary syndrome, and thromboembolism. ⁹ A study by Shih et al. demonstrated a higher rate of secondary coinfections in COVID‐19 positive patients with ARDS following extracorporeal membrane oxygenation placement, suggesting limited benefit of this rescue therapy. ¹⁰ This advocated for a standardized and documented approach to manage an ATAAD, where evidence is slowly growing on the optimal surgical approach, such as on the efficacy of valve‐sparing root replacement in ATAAD repairs. ¹¹ A study from Wang et al. alternatively provided insight into the use of triple branched stent graft implantation for ATAAD. ¹² This is a relatively novel approach to the management of ATAAD; a promising initial step for further investigations on the interplay between one surgical intervention and COVID‐19.

Despite no significant differences being found in operative outcomes in ATAAD operations during the pandemic when compared to prepandemic operative outcomes, the large heterogeneous patient demographic—4346 prepandemic and 1134 postpandemic identified in the retrospective cohort study by Arnaoutakis et al. enables for a high‐power interpretation. ⁸ Smaller studies looking at cardiac surgery outcomes show variance in COVID‐19 positive patient outcomes. A study by Saunders et al. compared mortality outcomes for patients with (n = 53) and without COVID‐19(n = 702) undergoing cardiac surgery, from nine UK centers. ⁴ Those with COVID‐19 had increased mortality (24.5% vs. 3.5%) and longer postoperative stay. Meanwhile, results from Hu et al.'s study comparing the short‐term outcomes of Stanford TAAD using Hubei Cardiac Surgery Registration System, showed in‐hospital deaths were 3.8% in both COVID and non‐COVID groups, although the COVID‐19 group was associated with longer ventilation and intensive care unit times. ¹³ However, there were no statistical differences between the two groups in the incidence of complications such as stroke, neurological deficit, acute kidney injury, pulmonary infection, and reoperation. ¹³ Unlike the studies from the literature Arnaoutakis et al. fails to quantify the number of COVID‐19 positive patients out of the 1134 individuals who underwent ATAAD. Therefore, outcomes between COVID positive patients and COVID negative patients cannot be compared. Without grouping this data, effects from confounding factors affecting operational outcomes, such as change in resource allocation during the pandemic and ICU bed availability cannot be distinguished from the effects of COVID‐19.

Arnaoutakis and colleagues categorized the two patient groups in a multivariable model looking at: demographic/socioeconomic status, hemodynamic/cardiac status, and risk factor variables. This was included in descriptive statistics using a logistic regression model, which showed the prevalence of comorbidities was not significantly different. However, using a logistic regression model hinders analysis of the severity of the comorbidities of the patients, which could be relevant when comparing outcomes. Rahman et al. found that patients with uncontrolled diabetes mellitus, hypertension, chronic obstructive pulmonary disease, and use of antidepressant drugs had worse recovery postsurgery. ¹⁴

COVID‐19 risks contributing to worsening outcomes for the above‐mentioned comorbidities due to disruptions caused by the pandemic, including stress and changes to routine care, diet, and physical activity. ¹⁵ An estimated 41% of US adults initially avoided or delayed medical care because of COVID‐19 concerns or were encouraged to postpone routine appointments with their health care team if determined to be at high risk for COVID‐19. ¹⁶ Using a multivariable linear regression model would enable comparison of the severity of comorbidities in pre‐ and postpandemic patient groups undergoing ATAAD. Despite uncontrolled hypertension increasing the risk of TAAD, Arnaoutakis et al. found a 30% reduction in patient volume presenting with ATAAD. ⁸ Therefore, further understanding of out‐of‐hospital mortality from ATAAD during the pandemic is required to quantify the effect of the pandemic on the incidence of ATAAD.

Due to variance in COVID‐19 rate, patient's vaccination status and advancement in surgical techniques—the generalizability of the results obtained by researchers such as Saunders et al., Hu et al., and Arnaoutakis in the beginning of the pandemic is reduced. COVID‐19 presents a dynamic period in healthcare where management and outcomes for ATAAD have changed dramatically since the start of the pandemic; example being vaccination status of patients—which Prasad et al. has shown to be associated with lower rates of postoperative morbidity and decreased length of hospital stay. ¹⁷

Advancement in surgical techniques such as use of triple branched stent implant, in selected patients, by Wang et al. has been shown to shorten intraoperative parameters such as cardiopulmonary bypass time, aortic cross‐clamp time, circulation arrest time, and the duration of ventilator‐assisted breathing. ¹³ Another promising step in advancement of ATAAD surgery is the use of the frozen elephant trunk technique (FET). A meta‐analysis conducted by Vernice and Wingo reported that FET had better 1 year survival rate and decreased perioperative mortality when compared to the conventional elephant trunk. ¹⁸ As advancement in surgical techniques improve mortality and perioperative outcomes, comparison of patient's pre‐pandemic and postpandemic to look at the effects of COVID‐19 becomes invalid in studies where patients' COVID‐19 status is not identified. ¹⁹ , ²⁰

There were no clear guidelines at the start of the COVID‐19 pandemic on the management of ATAAD. However, this has evolved as time has passed and major centers have adapted their practice subsequently. ¹⁹ , ²⁰ In general, Arnaoutakis et al. concluded similar operative outcomes of patients presenting to hospital with ATAAD whether they presented prepandemic or during the early pandemic phase. In addition, the pandemic caused a 30% reduction in presentation to hospital and the incidence of ATAAD repair according to the STS ACSD database decreased during the early phase. However, out‐of‐hospital mortality rates from ATAAD remain poorly documented in the literature. Therefore, this area requires further clinical data to scientifically draw evidence‐based guidelines and recommendations on the management of ATAAD during future pandemics.