Blood clots and COVID-19

There have been several articles on how patients with COVID-19 are prone to an increase blood coagulability. We caught Prof Tan Huay Cheem, Chairman of the Singapore Heart Foundation and Director of National University Heart Centre, Singapore; and Dr Mak Koon Hou, Assistant Honorary Secretary of the Singapore Heart Foundation and a cardiologist in private practice to find out more on the relationship between COVID-19 and blood clots.

How does COVID-19 form blood clots in a patient who has the virus?

Prof Tan: Coronaviruses are well known to increase blood coagulability. With an increased tendency towards blood clot formation within the circulatory system can result in serious complications such as stroke, heart attack, deep vein thrombosis causing pulmonary embolism (“economy class syndrome”) and gangrenous toes. Patients who are on haemodialysis are also noted to have an increased incidence of blocked tubes during their dialysis treatments due to clot formation.

A blood clot can form in an artery or vein in any part of the body. It can travel to other parts of the body. If it lodges in the heart or brain, blocking blood flow to these organs, it can result in a heart attack or stroke.

Dr Mak: In addition, patients who have a more severe condition, especially those who are immobilised, are more likely to have an increased risk of clot formation. In fact, a quarter to half of the patients with COVID-19 were detected to have clotting abnormalities. Those with a higher elevation of clotting were more likely to die.

Prof Tan: As such, high risk patients with COVID-19 are selectively given blood thinning medicines to prevent clot formation. There are also blood tests that can help identify patients who are at increased risk for clot formation.

Dr Mak: Patients with hypertension are at a higher risk of stroke and heart attacks. Therefore, it is important to control your blood pressure. Recognising this adverse manifestation of covid-19 can lead to an earlier institution of clot prevention.

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