This week's roundup of some of the latest scientific studies on the coronavirus and efforts to find treatments and vaccines for COVID-19 evaluates death risks after heart damage and often overlooked gastrointestinal symptoms, while also warning that the overuse of antibiotics could be the next epidemic the world has to face.

Higher death risk if COVID-19 affects heart

A new study may help identify which COVID-19 patients with signs of heart injury are at higher risk for death.

Doctors looked at 305 hospitalized patients with elevated levels of troponin, a protein released when the heart has been injured. They reported last week in the Journal of the American College of Cardiology that among these patients, the increased risk for death was statistically significant only when changes in the heart's size, shape, structure and function were seen during an echocardiogram.

Death rates were 5.2% in patients without troponin in their blood, 18.6% when troponin was high but hearts looked normal, and 31.7% in those with high troponin plus so-called heart remodeling. When other risk factors were considered, high troponin was only tied to death in patients who also had cardiac remodeling. COVID-19 patients with high troponin should undergo echocardiography "to guide further diagnostic testing and treatment strategies," coauthor Dr. Gennaro Giustino of Icahn School of Medicine at Mount Sinai in New York City told Reuters.

"Patients with a bad echo need much closer follow-up and more aggressive treatments," said Dr. Carl Lavie of Ochsner Health in New Orleans, who coauthored an editorial on the study.

Miniature lungs, colons help test COVID-19 treatments

Tiny organ-like structures grown in laboratories to behave like human lungs and colons can be used to rapidly screen drugs and identify those with potential as COVID-19 treatments, researchers reported in Nature.

Compared with traditional pre-clinical approaches, in which drugs are tested in cells from monkeys or from human cancer patients, these so-called organoids more faithfully mimic the complex cell types and structure of human tissues, according to Dr. Shuibing Chen and Dr. Robert Schwartz of Weill Cornell Medicine in New York.

Their team developed organoids containing types of lung and colon cells that are known to become infected in people with COVID-19. In collaboration with teams at Columbia University and Icahn School of Medicine at Mount Sinai, they screened 1,200 FDA-approved drugs and found three that showed activity against the coronavirus, including the cancer drug imatinib, sold as Gleevec by Novartis. It is currently being tested in four different COVID-19 clinical trials.

GI symptoms linked with more severe COVID-19

Gastrointestinal (GI) symptoms are associated with more severe COVID-19 and worse outcomes, two research teams have reported in a reversal of earlier data that suggested the opposite was true.

One team reviewed 38 earlier studies of a total of more than 8,400 patients and found those with diarrhea were 63% more likely to develop severe COVID-19. Dr. Subash Ghimire of Guthrie Robert Packer Hospital in Pennsylvania suggested that patients with diarrhea may have higher viral loads, which can potentially lead the body to fight back with more severe responses.

The other team studied 921 patients and found that the roughly 22% with at least one GI symptom had higher rates of hospital and intensive-care unit admissions and greater need for mechanical breathing assistance. The more GI symptoms patients had, the more their risk for these outcomes increased, Dr. Darbaz Adnan of Rush University Medical Center in Chicago reported. He said doctors evaluating COVID-19 patients need to bear in mind that GI symptoms may signal a markedly higher risk of a worsened disease course.

Both studies were presented at the American College of Gastroenterology virtual annual meeting.

Antibiotic overuse may be rising during pandemic

Unnecessary use of antibiotics, which can lead to harmful bacteria developing resistance to life-saving medicines, has been on the rise during the coronavirus pandemic, according to new research.

Data from 84 large U.S. Veterans Affairs facilities collected for the period of January through May over the last six years show that antibiotic use at those hospitals jumped during the initial COVID-19 surge, reversing a four-year downward trend. While antibiotic use fell steadily from 2015 to 2019, in 2020 it reached "levels not seen since 2016," Dr. Matthew Goetz of the VA Greater Los Angeles Healthcare System said on Friday during an annual meeting of infectious disease experts held virtually this year.

While the use of antibiotics was not directly linked to the number of COVID-19 patients being treated in each facility, "the pandemic provided new challenges to hospital systems that weren't prepared to manage it, from an onslaught of patients to a shortage of rapid diagnostic tests," Goetz said. The findings point to a weakening of antibiotic stewardship practices, he added.