key: cord-0982950-ktu01nct
authors: Tamargo, Juan
title: Does anticoagulation reduce mortality in patients with atrial fibrillation who later developed a COVID-19 infection?
date: 2021-01-27
journal: Int J Cardiol
DOI: 10.1016/j.ijcard.2021.01.019
sha: 09d6f6cf239fbdd62d282358d8d26e3ab7431688
doc_id: 982950
cord_uid: ktu01nct

nan

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndromecoronavirus-2 (SARS-CoV-2), is associated with a hypercoagulable state that increases the risk of venous and arterial thromboembolic complications [1, 2] . Despite anticoagulant therapy, these thromboembolic complications occurred in up to 69% in critically ill mechanically ventilated patients and post-mortem examinations have identified both macrovascular and microvascular thrombosis that may contribute to organ failure, multisystem injury and death, and clotting of circuits and vascular access have been well described in COVID-19-infected patients [1,2]. Thus, prophylactic and therapeutic antithrombotic therapy is recommended for hospitalized patients with COVID-19 to reduce morbidity and mortality regardless of the presence/absence of classical risk factors [1].

However, in the absence of randomized controlled trials or prospective data, the optimal prevention and treatment of thrombosis in COVID-19 remains uncertain and present evidence, mainly derived from retrospective studies (Table 1) , is contradictory [3] [4] [5] [6] .

In this issue of the International Journal of Cardiology, Denas et al [7] used a novel approach to obtain information on the effect of anticoagulation on COVID-19 morbidity and mortality. They retrospectively reviewed all elderly patients (≥ 65 years) from the Veneto Region with confirmed positive SARS-Covid-2 infection but, very smartly, compared patients who received chronic anticoagulation for atrial fibrillation (AF) with those who did not. Interestingly, AF is present in 10-36% in COVID-19 patients [8] . This high prevalence may be related to the observed increase in plasma angiotensin converting enzyme 2 (ACE2) activity, which is more marked in patients with persistent AF, and the presence of a systemic inflammatory response syndrome; both effects led to atrial electrical and structural remodelling, i.e. the arrhythmogenic substrate that increased cause mortality compared to their propensity score matched counterpart not on anticoagulant treatment. Nevertheless, the lower mortality observed in anticoagulated patients needs to be confirmed in further prospective randomized studies.

This study has some limitations, mainly due to its observational retrospective nature. Furthermore, authors did not take into account the anticoagulation that the patients received while in the intensive care unit or the influence of in-hospital interventions which might have affected the outcomes. Additionally, and even when a number of factors were included in their propensity score matching, they have missed some factors (i.e. illness severity) that could impact mortality, need for mechanical ventilation, or hospitalization. The finding that prediagnosis AC was not associated with a decreased rate of hospitalization, suggests that anticoagulation did not protect against development of severe COVID-19 disease. However, it has been hypothesized that if thrombotic complications are more a feature of later-stage disease, it is possible that administration of anticoagulation therapy early in the disease course may fail to detect later benefit [4] .

In conclusion, further prospective randomized trials, are urgently needed to assess the efficacy and safety of anticoagulant therapy, determine the optimal dose and course of prophylactic and therapeutic anticoagulation and identify those hospitalized patients with COVID-19 in whom this therapy confers a greater survival benefit. The results of several ongoing clinical trials (see clinicaltrials.gov) will shed light on these questions for which there is still no answer. 

Anticoagulant treatment is associated with decreased mortality in severe coronavirus disease 2019 patients with coagulopathy

Impact of anticoagulation prior to COVID-19 infection: a propensity score-matched cohort study

Association of treatment dose anticoagulation with in-hospital survival among hospitalized patients with COVID-19

Anticoagulation, Bleeding, Mortality, and Pathology in Hospitalized Patients With COVID-19

Reduction in allcause mortality in COVID-19 patients on chronic oral anticoagulation: A population-based propensity score matched study

Should atrial fibrillation be considered a cardiovascular risk factor for a worse prognosis in COVID-19 patients?

Atrial fibrillation

Angiotensin converting enzyme 2 activity and human atrial fibrillation: increased plasma angiotensin converting enzyme 2 activity is associated with atrial fibrillation and more advanced left atrial structural remodelling

Acknowledgments. This work was supported by Grants from the Institute of Health Carlos III (CB16/11/00303), Ministerio de Economía y Competitividad (SAF2017-88116-P) and Comunidad