To the editor,
Lodigiani et al.  provide valuable insight into the prevalence and time course of venous and arterial thromboembolism found in patients hospitalized for COVID 19. They note that 50% of thromboembolic events diagnosed in hospitalized COVID patients were discovered in the first 24 h of hospitalization and were likely present on admission. They raise the important point that pharmacological prophylaxis started upon hospitalization may have utility in preventing further venous thromboembolism (VTE) during hospitalization but is insufficient to treat the high proportion of VTE present upon admission. For newly admitted patients, they suggest employing a low threshold of suspicion to perform diagnostic imaging for pulmonary embolism (PE), the most common event found in this study.
The major factors arguing against obtaining CTPA (CT pulmonary angiogram) in hospitalized patients are patient respiratory or hemodynamic instability to undergo the test, and impaired renal function, risking contrast-induced nephropathy. Recent studies have demonstrated that screening immediately upon admission may mitigate some of those concerns. A large study of over 700 patients from China demonstrated that most acute kidney injury occurs a few days into hospitalization for patients with baseline elevated creatinine, and not for a week or more for patients with normal baseline creatinine . Additionally, in a large series of critically ill patients from New York, the median time to clinical deterioration requiring intensive care was 3 days . Both of these results support the authors' recommendation for a low threshold for obtaining CTPA (or perhaps instituting screening CTPA) upon admission for hospitalized COVID patients, while the overall clinical status and renal function permit. While the question of utilizing therapeutic vs. prophylactic dose anticoagulation remains yet unanswered in these patients, Lodigiani et al. provide convincing evidence that a business-as-usual approach is clearly insufficient.