In addition to the direct effects of the SARS-CoV-2 virus and the typical manifestations of covid-19, several studies have found a higher than expected proportion of patients suffer abnormal blood clot formation, or what physicians call thrombotic events. These events include blood clots in the lungs (pulmonary embolisms, or "PEs"), clots in veins of the legs and/or arms (deep vein thrombosis), as well as strokes, and heart attacks. These conditions can be serious enough to be life-threatening, though many can be mild, especially if treated appropriately.
Most of the research describing the potential increase in these conditions which are thought to be among the many complications of covid-19 has been performed in the inpatient hospital setting, where patients are generally on the sicker end of the spectrum, and in whom, the baseline occurrence of these disease processes may be more common.
Now, in the journal Academic Emergency Medicine, a group of researchers have reported data from a single-center retrospective study in which they assessed the number of computed tomographic pulmonary angiograms (CTPAs) ordered by emergency physicians looking either to diagnose or rule out pulmonary embolisms (blood clots in the lungs). They gathered data from April 1 through May 1, 2020 and compared the findings with data from the same time period in 2019.
In 2020, two times as many CTPAs were positive for blood clots in the lung compared 2019 (19 percent versus 8 percent). Over half of the patients with blood clots in the lungs (60 percent) in 2020 were positive for SARS-CoV-2, 88 percent of whom tested positive during the same emergency department visit, rather than during prior medical encounters, either in the emergency department, or any other clinical setting.
These data add to the emerging literature suggesting SARS-CoV-2 may increase the risk of blood clots to the lungs. However, there are several potential alternative explanations for these findings, including a change in the composition of emergency department patients during the peaks of covid-19 surges; while nationwide, fewer patients were treated in emergency departments overall during the study period, those that were seen and treated may have been sicker than the typical complement of patients. Further, there may have been changes in clinician practice patterns and decisions regarding who was determined to require testing for these clots may have changed.
Regardless, this study provides an important reminder to avoid what physicians call "premature diagnostic closure"; while the symptoms of covid-19 and blood clots in the lungs may be similar (shortness of breath, low oxygen saturations, for example) and patients may have a positive test for SARS-CoV-2, these patients could still also have pulmonary embolisms simultaneously.