Patients with coronavirus have a number of coagulation (blot clots) abnormalities which can result in excessive tendency towards creating clots (thrombosis) and it is clear from the evidence that this may be a big risk factor for death in severely ill patients and needs to be carefully treated and studied further. The mechanisms are not currently well understood but involve:
- Endothelial injury
Clinical feature can include, often despite prophylactic-dose anticoagulation:
- Venous thromboembolism including extensive deep vein thrombosis
- Pulmonary embolism which is seen in up to one-third of patients in the ICU even when anticoagulation is given.
Autopsy studies also demonstrate that hypercoagulability is common in the most severely ill patients. In one study where a post-mortem was performed on 21 patients that died from coronavirus, a pulmonary embolism was found in four and in those who had the data available and it was found that almost 50% of the deceased had mircrothombi in alveolar capillaries.
In another study of 12 post-mortem examinations 7 of 12 had bilateral deep vein thrombosis (clots) in the legs with all cases having been both bilateral and interestingly unsuspected in all patients. Of those 12 – the cause of death in at least 4 was determined to be a pulmonary embolism – clots in the lungs.
Studies also demonstrate that widespread clothing and micro clots were significantly more prominent in the lungs of the patients who died of coronavirus compared with the lungs of controls who died of for example the flu.
Risk factors for hypercoagulability
Studies indicate – due to the fact that most patients have risks such as obese males, other medical conditions with heart disease, high blood pressure and diabetes being common.
Other clinical presentations
The data regarding how the tendency for thrombosis can present includes:
- Arterial events such as an increased incidence of strokes,
- acute limb ischemia,
- potentially heart attacks and
- microvascular clotting and even bleeding.