To the Editor:

We would like to thank Muller et al.1 for their thoughtful letter and for sharing some of their data from the Netherlands regarding the impact of coronavirus disease 2019 (COVID-19) on patients with implanted left ventricular assist devices (LVADs).

Muller et al.1 described a population of LVAD patients that were younger, had less comorbid conditions, and a lower median body mass index (BMI), which likely contributed to their lower COVID-19–related hospitalization and mortality rates. Comparatively, our patient population was older (65 vs. 54 years of age), had more comorbid conditions (43% vs. 0% of diabetes), and a higher BMI (27 vs. 24 kg/m2), with 29% of our patients having a BMI greater than or equal to 30 kg/m2. As described in our study,2 these are some factors that likely contributed to more severe COVID-19 infections. Obesity specifically has been associated with a higher risk of morbidity and mortality in patients with COVID-19, including a higher risk of supplemental oxygen, intensive care unit (ICU) admission, and death.3 In addition, a large portion of our hospitalized patients were diagnosed and treated in the early stages of the pandemic when testing was limited and performed mostly in symptomatic patients presenting to the emergency department. At that stage, most recommended treatment protocols and medical therapies, including the use of vaccines and outpatient monoclonal antibody infusions, were not yet available. We agree with Muller et al.,1 that this may have created a selection bias for symptomatic LVAD patients with COVID-19, while vaccinated or asymptomatic patients with milder cases were not included in our cohort.

Studies have also shown that demographic differences between patient populations are associated with certain groups having a higher likelihood in contracting COVID-19 and experiencing higher morbidity, in part due to less readily available healthcare services and treatment modalities.4 Further investigation into these disparities and into the impact they have on LVAD specific patient populations from a national and international perspective is warranted when comparing outcomes.

Despite the findings by Muller et al.,1 we believe that LVAD patients are at an increased risk of morbidity and mortality from COVID-19 due to an immunocompromised state, often in the setting of multiple underlying medical conditions, and physiologic (mal)adaptations due to the mechanical circulatory support of continuous flow devices. While there have been many systems-based changes throughout the pandemic including increased availability and convenience of rapid testing, more evidence-based guidelines for the tirage and treatment of patients, as well as the availability of vaccines, LVAD patients should continue to be closely monitored and more often treated aggressively with outpatient antiviral therapies as they become more readily available to avoid debilitating illness from COVID-19.

References 1. Muller SA, van der Meer MG, Szymanksi MK, et al.: Letter by Muller et al regarding article “Impact of COVID-19 on Patients Supported with a Left Ventricular Assist Device.” ASAIO J 68: e156, 2022. 2. Zakrzewski J, Coyle L, Aicher T, et al.: Impact of COVID-19 on patients supported with a left ventricular assist device. ASAIO J 67: 1189–1195, 2021. 3. Huang Y, Lu Y, Huang YM, et al.: Obesity in patients with COVID-19: A review and meta-analysis. Metabolism 113: 154378, 2020. 4. Mackey K, Ayers CK, Kondo KK, et al.: Racial and ethnic disparities in COVID-19-related infections, hospitalizations, and deaths: A systematic review. Ann Intern Med 174: 362–373, 2021.