Acute Pulmonary Artery Thrombosis despite Anticoagulation in Patients with COVID-19 Pneumonia: A Single-Center Retrospective Cohort Study

Abstract

(1) Background: We aimed to describe the clinical and imaging characteristics of patients diagnosed with pulmonary artery thrombosis (PAT) despite receiving anticoagulation with low-molecular-weight heparin (LMWH). (2) Methods: We retrospectively studied all hospitalized COVID-19 adult patients diagnosed with PAT between March 2020 and December 2021, who received LMWH for ≥72 h until the diagnosis of PAT. Acute PAT was confirmed by a CT pulmonary angiogram. (3) Results: We included 30 severe and critical COVID-19 patients. Median age was 62 (54–74) years, with 83.3% males, and comorbidities seen in 73.3%. PAT was diagnosed despite prophylactic (23.3%), intermediate (46.6%) or therapeutic (30%) doses of LMWH for a median time of 8 (4.7–12) days. According to their Wells score, 80% of patients had a low probability of pulmonary embolism diagnosis. PAT was localized in the lower lobes of the lungs in 76.6% of cases with 33.3% having bilateral involvement, with the distal, peripheral arteries being the most affected. At the PAT diagnosis we found a worsening of respiratory function, with seven patients progressing to mechanical ventilation (p = 0.006). The in-hospital mortality was 30%. (4) Conclusions: PAT should be considered in patients with severe and critical COVID-19, mainly in elderly male patients with comorbidities, irrespective of Wells score and LMWH anticoagulation.

Mechanisms of COVID-19 Associated Pulmonary Thrombosis: A Narrative Review

“…COVID-19-associated thrombotic complications could develop despite standard prophylactic anticoagulation, suggesting that a therapeutic anticoagulation or alternative antithrombotic agents could have much better results [ 11 , 19 , 173 , 174 ]. The failure of anticoagulation for preventing pulmonary artery thrombosis was also reported by some clinical studies on COVID-19 patients [ 33 , 147 , 168 , 175 , 176 ]. In patients with severe COVID-19, the poor response to systemic anticoagulation is supported not only by clinical studies, but also by histological examination of the lung tissue, which described a diffuse arterial thrombosis in the lungs secondary to vascular inflammatory and prothrombotic changes and hypoperfusion [ 177 ].…”

“…Diffuse, segmental/subsegmental thrombosis is predominant in COVID-19 patients [ 33 , 34 , 144 , 145 , 146 , 147 ]. As small peripheral lung thrombi are more prevalent in COVID-19, evaluating the subsegmental pulmonary arteries by computed tomography pulmonary angiogram is essential [ 33 , 148 , 149 ].…”

“…In another paper, the distribution of thrombosis correlated with the pattern of consolidation, and in 93% of cases, it involved peripheral or subsegmental arteries [ 152 ]. Patients with pulmonary artery thrombosis have significantly higher inflammatory lesions on chest CT analysis compared to those without thrombosis, especially in the lower lobes of the lungs, where blood clots predominate [ 5 , 147 , 153 ]. When analyzing quantitative chest CT data in patients with SARS-CoV-2 pneumonia and pulmonary thrombosis, more than half of them had more than 50% COVID-19-associated lung involvement, which is also associated with a higher mortality [ 147 , 154 , 155 ].…”

“…The use of intermediate instead of standard doses of prophylactic anticoagulants did not result in lower incidence of thrombosis or mortality in critically ill COVID-19 patients [ 178 ]. Pulmonary artery thrombosis and DVT reported in hospitalized patients with COVID-19 could develop despite prophylactic, intermediate, and therapeutic doses of anticoagulation [ 33 , 147 , 168 ]. In most studies, low-molecular-weight heparins (LMWHs) were used for prophylaxis of thrombosis.…”

Quantitative chest CT imaging characteristics and outcome of patients with COVID-19 associated pulmonary artery thrombosis: A single-center retrospective cohort study

“…[9–16] Moreover, chest imaging data of patients with SARS-CoV-2 infection could be used to analyze the association between lung inflammatory lesions and in situ vascular thrombosis. [8,14,17–19]…”