Insidious development of pulmonary embolism in asymptomatic patients with COVID-19: Two rare case-reports.

Scarce data exist regarding the clinical sequelae of COVID-19 and/or the prevalence of thromboembolic disease in asymptomatic patients. Surely, there is increased prevalence of thromboembolic disease and pulmonary embolism (PE) in critically ill patients with COVID-19; hence the administration of even enhanced thromboprophylaxis was suggested. However, the administration of regular thromboprophylaxis in asymptomatic outpatients is an entirely different matter. Herein, we present the clinical story of insidious PE development in two asymptomatic COVID-19 female patients. Issues regarding the pathogenesis of thromboembolism in COVID-19 and the clinical management are equally discussed.

COVID-19

intensive care unit

Real-Time-Polymerase-Chain-Reaction

computed tomography

high flow nasal cannula

deep vein thrombosis

pulmonary embolism

World Health Organization

Fraction of inspired oxygen

saturation of peripheral oxygen

renin-angiotensin-aldosterone system

Introduction

The novel coronavirus SARS-CoV-2 disease (COVID-19) pandemic emerged in China and spread worldwide. The dominant transmission mode of COVID-19 is human-to-human transmission with most cases being asymptomatic [1]. However, life-threatening disease can occur, in a few patients, which is usually characterized by acute respiratory distress syndrome, sepsis, multi-system organ failure, neurological manifestations, and thromboembolic disease [[1], [2], [3], [4]]. An increased prevalence of pulmonary embolism (PE) and thromboembolic phenomena were described in critically ill mechanically ventilated patients with COVID-19 [5,6]. The development of a hypercoagulable state with associated vascular dysfunction and cytokine storm, promoting thus thromboinflammation was suggested [7,8]. This exaggerated inflammatory immune response and thrombotic microangiopathy resulting in multi-organ dysfunction and death was confirmed by post-mortem studies [9]. PE was mainly described in COVID-19 patients with concomitant lung parenchymal injury, which was characterized, in the majority of cases, by peripheral ground-glass opacities in chest computed tomography (CT) studies [[10], [11], [12], [13], [14]]. Asymptomatic carriers of COVID-19 were discovered among close contacts of confirmed cases [15]; however, the epidemiological significance of asymptomatic infections remains obscure. Also, scarce data exist regarding the clinical sequelae of COVID-19 and/or the prevalence of thromboembolic disease in asymptomatic patients [16,17]. Herein, we present two rare cases of insidious PE development in two asymptomatic COVID-19 female carriers.

Case presentation

Case 1

A previously healthy 50 year old female was tested for COVID-19 by Real-Time-Polymerase-Chain-Reaction (RT-PCR) assays [[18], [19], [20]], performed on nasopharyngeal swabs, using QuantiNova Probe RT-PCR kit (Qiagen) in a Light-Cycler 480 real-time PCR system (Roche, Basel, Switzerland) as per Saudi Ministry of Health [21], and World Health Organization (WHO) guidelines [22]. The patient was tested due to close unprotected contact with her husband who recovered from COVID-19. She was asymptomatic but was evaluated in the emergency department and underwent chest CT scan to exclude any pulmonary involvement nevertheless [[23], [24], [25]]. The patient tested positive for COVID-19, while her husband's test was negative at that time (baseline). She was entirely asymptomatic; while her chest CT scan and laboratory findings were normal. We discharged her to home isolation and prescribed multivitamins including vitamin C and zinc. However, after twenty days, the female patient was readmitted to the emergency department due to recent onset shortness of breath, chest pain and leg swelling (Fig. 1). Physical examination was normal apart from the swelling of the right lower limb. The saturation of peripheral oxygen (SpO2) was 80% (room air). She was connected to a high flow nasal cannula [(HFNC) with a flow of 60 L/min, and fraction of inspired oxygen (FiO2) of 40%] maintaining SpO2 of 94%. Repeat RT-PCR test for COVID-19 was positive. Deep vein thrombosis (DVT) was clinically suspected and thereafter confirmed by Duplex ultrasound examination. The latter revealed acute thrombosis of the right external iliac and common femoral veins (Fig. 1). Echocardiography and cardiac enzymes were normal. Contrast chest CT scan revealed pulmonary embolism but no parenchymal lung involvement (Fig. 1). She was admitted to a negative pressure isolation room in the intensive care unit (ICU) for close observation. Baseline laboratory findings were normal apart from lymphocytopenia (0.55 × 10⁹/L, normal: 1.1–3.2 × 10⁹/L), and increased C-reactive protein (81 mg/liter, normal: 0–7 mg/liter), and D-dimers (7.5 mcg/ml, normal: 0 to 0.5 mcg/ml). We administered empiric treatment with ribavirin/interferon beta-1b, and therapeutic anticoagulation adjusted to her body weight as per hospital protocol [21] (Padua prediction score = 4). A full diagnostic work-up for other viral and systemic disorders including thrombophilia screening was negative. On day-22 post-ICU admission, RT-PCR test for COVID-19 and microbiology were negative. She was discharged to home isolation. Oral rivaroxaban was prescribed for three months, and the patient is closely followed-up by her cardiologist [26].

Fig. 1

Clinical course of our asymptomatic COVID-19 patient (case 1) from baseline to the development of deep vein thrombosis of the right external iliac and femoral veins as depicted by duplex ultrasound; and pulmonary embolism as depicted by contrast chest computed tomography, which revealed filling defects of segmental and lower lobular branches of the right pulmonary artery. Finally the patient was discharged on rivaroxaban therapy.

Case 2

A previously healthy 56 year old female was tested for COVID-19 by Real-Time-Polymerase-Chain-Reaction (RT-PCR) assays, performed on nasopharyngeal swabs, as described in aforementioned paragraphs [[18], [19], [20], [21], [22]]. The patient was admitted to the emergency department as she was worried of SARS-CoV-2 infection after close unprotected contact with her daughter who recovered from COVID-19. She tested positive for COVID-19 although she was entirely asymptomatic (baseline). Chest CT scan and laboratory examinations were normal. The patient was discharged to home isolation. After thirty five days, the patient was readmitted to the emergency department due to shortness of breath, chest pain, and low-grade fever (Fig. 2). Physical examination was normal. The saturation of peripheral oxygen (SpO2) was 79% (room air). She was connected to HFNC with a flow of 60 L/min, and fraction of inspired oxygen (FiO2) of 40%] maintaining SpO2 of 92%. Repeat RT-PCR test for COVID-19 was positive. We suspected PE, which was confirmed by contrast chest CT, but no lung parenchymal involvement was documented (Fig. 2). Also, DVT was excluded by Duplex ultrasound examination. Echocardiography and cardiac enzymes were normal. Although the patient was hemodynamically stable, she was admitted to a negative pressure ICU isolation room for observation. Baseline laboratory findings were normal apart from lymphocytopenia (0.62 × 10⁹/L, normal: 1.1–3.2 × 10⁹/L), and increased C-reactive protein (101 mg/liter, normal: 0–7 mg/liter), and D-dimers (7.1 mcg/ml, normal: 0 to 0.5 mcg/ml). We administered empiric treatment with ribavirin/interferon beta-1b, and therapeutic anticoagulation adjusted to her body weight as per hospital protocol (Padua prediction score = 4). A full diagnostic work-up for other viral, microbial and systemic disorders including thrombophilia screening was negative. On day-19 post-ICU admission, RT-PCR test for COVID-19 and microbiology were negative. She was discharged to home isolation, and oral rivaroxaban was prescribed for three months. The patient is followed-up by her family physician.

Fig. 2

Clinical course of our asymptomatic COVID-19 patient (case 2) from baseline to the development of pulmonary embolism as depicted by contrast chest computed tomography, which revealed multiple filling defects of segmental and lower lobular branches of the right pulmonary artery. Finally the patient was discharged on rivaroxaban therapy.

Discussion

The clinical sequelae of COVID-19 and/or the prevalence of thromboembolic disease in asymptomatic patients remain partially studied. PE and thromboembolic disease were linked to critically ill patients with COVID-19. These pathologies can have a detrimental effect on morbidity and mortality [27]. The pathology of COVID19 is not yet elucidated, but it is acknowledged there is a thromboinflammatory basis, which is characterized by lymphocytopenia, and increased levels of D-dimer, CRP, other inflammatory mediators, and cytokines (i.e., interleukin-6) [[7], [8], [9],[28], [29], [30], [31]]. We present two asymptomatic female COVID-19 carriers, which were initially infected with SARS-CoV-2 due to unprotected contact with patients who were living with them. The first case presented with acute DVT and PE without any lung parenchymal involvement, twenty days after she initially tested positive for COVID-19. We are uncertain whether the persistent COVID-19 status might be attributed to a putative reinfection or, most probably, to recurrently positive RT-PCR results. DVT with accompanying PE in COVID-19 was described in various studies; however patients were symptomatic and/or critically ill [6,27,32]. Our second case presented with the same clinical features, but with “isolated” PE without any DVT. The aforementioned concerns apply on this case as well regarding the COVID-19 status from baseline to the presentation of PE.

Our patients were both asymptomatic and had no predisposing factors for thromboembolic disease. They presented with lymphocytopenia, and increased levels of D-dimer, while their Padua prediction score was 4. Recently, the administration of enhanced anticoagulation in patients with severe COVID-19, and Padua prediction score ≥4 or D-dimer>3.0 μg/mL was suggested [33]. Although prophylactic anticoagulation should be applied on all hospitalized COVID-19 patients [33,34], we are uncertain whether this could be also considered for outpatients with mild disease or no symptoms. SARS-CoV-2 can bind via its spike protein to the angiotensin-converting enzyme 2 (ACE2) receptor resulting thus in endothelial inflammation [35]. Hence, the underlying pathophysiology may range from direct viral toxicity and thromboinflammation to dysregulated immune system and renin-angiotensin-aldosterone system (RAAS) responses. Moreover, it was suggested that the organotropism of SARS-CoV-2 could be mediated via the dysregulated RAAS response and associated cytokine storm [7,8,35]. Our group recently developed the theory of “fragile endothelium” in an effort to explain the versatile attack of the virus on several vascular territories [36]. We speculated that a vascular topographic viral tropism exists and could be partially mediated via the dysregulated immune and RAAS response and other neurochemical alterations. This theory might at least partially explain the diverse features of thromboembolic disease in COVID-19 (attack on different vascular territories based on the viral tropism creating thus different areas of “fragile endothelium” that is prone to thromboinflammation), which is further observed in clinical and post-mortem studies [4,6,[8], [9], [10],29,32,37,38]. Whether the application of immunomodulation such as interleukin-6 blockade via tozilizumab, and plasma exchange therapies may reduce the risk of developing thromboembolism in COVID-19 remains unclear and should be further investigated [28,[39], [40], [41], [42]].

These two rare-case reports, albeit their limitations, describe the insidious development of PE in asymptomatic COVID-19 patients who did not have any other risk factors for thromboembolic disease. Surely, the administration of enhanced anticoagulation in critically ill patients with COVID-19 and increased Padua prediction score and/or elevated D-dimers warrants further attention bearing in mind that a risk of bleeding also exists. However, the administration of prophylactic anticoagulation to asymptomatic carriers is an entirely new subject that needs to be further clarified. The natural course of SARS-CoV-2 viremia remains obscure as reinfections and/or recurrently positive RT-PCR results were previously described [[43], [44], [45], [46]]. We have prescribed a new oral anticoagulant that may be useful in preventing future thromboembolic phenomena as SARS-CoV-2 reinfection and/or natural immunity remain obscure [26,27]. Currently, both patients are under follow-up to determine any side-effects of therapy (i.e., bleeding episodes). In conclusion, asymptomatic COVID-19 patients may exhibit versatile underlying pathophysiology, which could promote the insidious onset of thromboembolic phenomena related to their COVID-19 status. Future large prospective studies are clearly required to refute or confirm the present findings.

Credit authorship contribution statement

Abdullah Balahmar: Validation, Writing-original draft.

Abdulrahman Alharthy: Conceptualization, Investigation, Validation, and Writing-original draft.

Fahad Faqihi: Investigation, Validation, Writing-original draft.

Rayan Alshaya: Investigation, Validation, Writing-original draft.

Alfateh Noor: Investigation, Validation, and Data Analysis.

Feisal AlAklobi: Investigation, Validation, Writing-original draft.

Ziad A Memish: Validation, Supervision, review & editing the final draft.

Dimitrios Karakitsos: Conceptualization, review & editing the final draft.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Ethical approval

The study was approved by the Institutional Review Board of King Saud Medical City, Riyadh, Kingdom of Saudi Arabia [H-01-R-053, IORG0010374, H1RI-7-20-01]. Written informed consent was obtained from the patients.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.