Preventing blood clots is becoming a crucial part of caring for COVID-19 patients, both in the hospital and after they leave

• As the coronavirus pandemic persists in the US, doctors are learning more about some of the harmful complications associated with COVID-19.
• Treating blood clots in COVID-19 patients has become an integral part of how hospitals are taking care of people with the disease.
• In some hospitals, doctors are getting coronavirus patients started on blood thinners earlier. Some are sending patients home with blood thinner prescriptions, too.
• "There's absolutely no question that physicians really need to have blood clots on their radar screen," Dr. Mark Crowther, the treasurer of the American Society of Hematology, told Business Insider.
• Visit Business Insider's homepage for more stories.

New York hospitals learned a lot about COVID-19, the disease caused by the novel coronavirus, as the state has tackled the outbreak.

At times, the hospitals were overwhelmed with patients, many of whom died. It was a deadly month for the state.

As the coronavirus pandemic spread, infecting millions globally and killing hundreds of thousands, doctors have been forced to rapidly figure out how to treat it without a vaccine or medicines that cure it. They're still not sure of the best way to get oxygen into the damaged lungs of the most severely ill patients, for example.

Maimonides Medical Center in Brooklyn approach to caring for patients with the disease, from treating blood clots to using ventilators, evolved, Dr. Patrick Borgen, the hospital's chief of surgery, told Business Insider.

In particular, the emergence of blood clots as a severe complication related to COVID-19 has changed the way the hospital treats all COVID-19 patients from the minute they're hospitalized, Borgen said.

About a month ago, the complication wasn't even on the hospital's radar.

"We began to understand just how much blood clotting was a part of the COVID story," Borgen said.

Clots can wreak havoc on the body, traveling and blocking up veins, leading to strokes, heart attacks, kidney problems, lung problems, and more. They're common in hospitalized patients, but appear to be happening more frequently in COVID-19 patients severely ill with the disease.

To counter that, Borgen said the hospital now keeps an even closer eye on them, using anticoagulation treatments to keep patients' blood from clotting throughout their hospital stay. The hospital is also discharging patients on blood-thinning medication, he said.

Hospitals around the country now are beginning to address clotting as a concern related to COVID-19.

Clotting complications appear to pop up in about 10% of all hospitalized COVID-19 cases, according to data seen by Dr. Mark Crowther, the chair of the department of medicine at McMaster University in Ontario, Canada and the treasurer of the American Society of Hematology.

"There's absolutely no question that physicians really need to have blood clots on their radar screen," Crowther said. "If you fail to consider it, you can get into trouble pretty quickly."

COVID-19's impact goes beyond the lungs

Dr. Ed Kuffner, an emergency-medicine physician by training, volunteered in the emergency room of NYC Health + Hospitals/Coney Island during the pandemic.

Kuffner, who's now the chief medical officer at Johnson & Johnson's consumer companies, said caring for COVID-19 patients showed him that the disease did more than just impact a person's lungs.

"I had in my head it was primarily if not exclusively a pulmonary disease," Kuffner said.

Over time, he realized that wasn't the case. Yes, a lot of the severe complications have to do with the lungs, but he saw it affecting all organs. For instance, over time he started putting patients on full anticoagulation doses when they came into the emergency room, rather than the lower preventive doses, Kuffner said.

"I started to realize that what I went in thinking really wasn't the true extent of COVID-19," Kuffner.

In the case of COVID-19, where the risk of clotting appears to be higher than in a typical hospitalization, Crowther said he expects to see more hospitals prescribing preventive doses of blood thinners to more patients as they leave the hospital than they might otherwise.

Crowther said there's evidence that providing blood thinners to patients after they leave the hospital on the whole lowers the risk of clotting incidents.

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Treating clotting complications in COVID-19 patients

In the absence of sturdy scientific evidence backing up whether one approach or another is best, doctors are debating the best way to treat the disease, especially in critically ill patients. Studies are ongoing on whether clot-busting drugs — typically used to treat strokes — are a better approach.

Early on in the coronavirus outbreak, doctors in the US were hearing from colleagues in China about the virus' effects on the heart, Dr. Thomas Maddox, who serves as chair of the science and quality committee of the American College of Cardiology, told Business Insider in an April interview.

The effects seemed to be related to both a viral invasion of the heart and to the stress of fighting the respiratory disease.

With COVID-19, doctors are also seeing blood clots occurring in the lungs and bodies of patients on ventilators, Dr. Greg Martin, a professor of pulmonary critical care at Emory University and president-elect of the Society of Critical Care Medicine, previously told Business Insider.

Other viruses can cause blood problems as well, Crowther noted. For instance, Ebola causes bleeding.

Also, blood clots aren't uncommon in severely ill patients in intensive care units, or even in hospitalizations. While in the ICU, patients are typically on breathing support and sedated, which limits their ability to move as they heal. Staying still raises the risk of clots.

But the rate at which clots are popping up appears to be higher in critically ill COVID-19 patients. In a recent observational study, Dutch researchers reported that about one-third of the 184 coronavirus patients they observed in the intensive-care unit had a complication associated with a clot.

"We think it's one of the most important, if not the most important, issue with respect to monitoring sick hospitalized COVID-19 patients," Dr. Alex Spyropoulos, an expert on blood clots at Northwell Health in New York said in an April interview.

Clotting occurring outside the hospital

For now, most of the conversation is about what to do to prevent blood clot complications in hospitalized patients.

But, researchers are wondering whether clotting complications are happening in milder COVID-19 cases that don't require a hospital stay. That's a question that's far from being answered, particularly given the lack of routine testing available.

The other question is whether blood clots are causing problems after COVID-19 patients leave the hospital, leading to sudden deaths. Spyropolous said he's concerned about complications arising after patients are discharged.

In early autopsy data from Northwell, there appear to be major clotting events like a massive heart attack or lung clots in 40% of patients who have died after leaving the hospital, Business Insider previously reported.

Michael Reagan, a 49-year-old COVID-19 patient, told Business Insider he was recovering from the illness when doctors found blood clots in his lungs. After an overnight stay, Reagan was sent home with a prescription for a blood thinner.

"It feels like a toxin is in my body," Reagan told Business Insider in April.

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