High rates of pulmonary artery occlusions in COVID‐19. A meta‐analysis

Abstract

Background COVID‐19 patients are considered at high risk of venous thromboembolism (VTE). The real nature of pulmonary artery occlusions (PAO) in COVID‐19 has been questioned, suggesting that it is caused also by in situ thrombi, rather than only by emboli (PE) from peripheral thrombi. Methods We searched MEDLINE for studies published until 6 June 2020 that included COVID‐19 patients or non‐COVID‐19 medical patients at VTE risk, treated with heparins, in whom VTE (PE and deep vein thrombosis, DVT) had been reported. Systematic review and results reporting were conducted in accordance with PRISMA guidelines. Data were independently extracted by two observers, and estimates were pooled using random‐effects meta‐analysis. Results We identified 17 studies including 3224 COVID‐19 patients and 7 including 11 985 non‐COVID‐19 patients. Two analyses were performed: in all COVID‐19 patients and only in those (n = 515) who, like non‐COVID‐19 patients, were screened systematically for DVT. The latter analysis revealed that the prevalence of DVT was 15.43% (95%CI, 4.08‐31.77) in COVID‐19 and 4.21% (2.27‐6.68) in non‐COVID‐19 patients (P = .0482). The prevalence of PE was 4.85% (40.33‐13.01) in COVID‐19 patients and 0.22% (0.03‐0.55) in non‐COVID‐19 patients (P = .0128). The percentage of PE among VTE events was 22.15% (5.31‐44.60) in COVID‐19 and 6.39% (3.17‐10.41) in non‐COVID‐19 patients (P = .0482). Differences were even more marked when all COVID‐19 patients were analysed. Conclusions The results of our meta‐analysis highlight a disproportion in the prevalence of PE among all VTE events in COVID 19 patients, likely reflecting PAO by pulmonary thrombi, rather than emboli from peripheral vein thrombi.

The Many Faces of Covid-19 at a Glance: A University Hospital Multidisciplinary Account From Milan, Italy

“…In non-ICU wards, the frequency of DVT was low and similar in Covid-19 (4.57%) and non-Covid-19 patients (3.64%), suggesting that the risk of DVT is not higher in Covid-19 than in non-Covid-19 patients. In contrast the frequency of “pulmonary artery occlusions” was much higher in Covid-19 patients (2.55%) than in non-Covid-19 patients (0.11%), thus supporting our hypothesis that most pulmonary artery occlusions in Covid-19 are attributable to pulmonary artery thrombosis, rather than pulmonary emboli ( 32 ).…”

“…We hypothesized that the described pulmonary vascular occlusions are accounted for by pulmonary artery thrombosis, rather than pulmonary embolism ( 31 ), considering the low reported incidence of DVT, which represent the origin of pulmonary emboli ( 30 ). A recent meta-analysis by our internal medicine group compared the frequencies of DVT and “pulmonary artery occlusion” in patients with Covid-19 with those observed in previously reported patients without Covid-19: all had been under thromboprophylaxis with low-dose heparin ( 32 ). In non-ICU wards, the frequency of DVT was low and similar in Covid-19 (4.57%) and non-Covid-19 patients (3.64%), suggesting that the risk of DVT is not higher in Covid-19 than in non-Covid-19 patients.…”

Long‐term follow‐up of patients with venous thromboembolism and COVID‐19: Analysis of risk factors for death and major bleeding

“…In the previously mentioned RIETE Registry study, 83% of COVID‐19 patients with VTE had acute PE, while only 17% had isolated DVT 17 . A meta‐analysis that included COVID‐19 or non‐COVID‐19 patients showed that the pooled percentage of PE among all VTE patients was significantly higher in COVID‐19 compared with non‐COVID‐19 patients (22.1% vs 6.4% P = .048) in studies in which DVT was systematically screened by CUS (compression ultrasonography) 21 . Emerging data regarding the discrepancy between the rate of DVT and PE in COVID‐19 patients, and the fact that many of the documented cases of PE occur in the absence of DVT and are located in the more peripheral pulmonary arteries 22 have led to the hypothesis that there may be a unique PE phenotype in these patients, characterized by thrombi and not emboli—that is, immunothrombosis—is probably much more prominent than originally recognized 23 …”

Similarities and perspectives on the two C’s—Cancer and COVID‐19

“…31 A recent meta-analysis identified that a high proportion of thrombotic events in COVID-19 patients are likely to be secondary to pulmonary artery occlusion by thrombi, rather than emboli from peripheral vein thrombi. 32 In both COVID-19 and malignancies, there is marked activation of coagulation, which increases thrombotic risk anywhere in the circulatory system and not exclusively in the lower limb veins. The key trigger for thrombosis here is the aggressiveness of the underlying malignancy or the degree of inflammation in COVID-19.…”

“…Similarly, in COVID‐19, the thrombo‐inflammatory process that commences in the lungs would cause pulmonary thrombi at least in the initial stages and surveillance Doppler imaging for DVT may not serve as surrogate for pulmonary thrombi 31 . A recent meta‐analysis identified that a high proportion of thrombotic events in COVID‐19 patients are likely to be secondary to pulmonary artery occlusion by thrombi, rather than emboli from peripheral vein thrombi 32 . In both COVID‐19 and malignancies, there is marked activation of coagulation, which increases thrombotic risk anywhere in the circulatory system and not exclusively in the lower limb veins.…”