There is increasing evidence that COVID-19 induces endothelial dysfunction that may precede thrombotic and cardiovascular complications. The aim of this study is to evaluate endothelial function using peripheral arterial tonometry (EndoPAT). The primary endpoint is the hyperemic vascular response index (LnRHI) at two months post-discharge. Secondary endpoints include the LnRHI during hospitalization and at six-month follow-up, the proportion of patients with endothelial dysfunction (LnRHI ≤ 0.51), and the incidence of thrombotic events, cardiovascular complications, and mortality during the follow-up period. The study included 23 COVID-19 patients and 22 COVID-19-negative, matched controls. The patients exhibited a significant reduction in the LnRHI at two months post-discharge compared to the controls (median = 0.55 [IQR: 0.49–0.68] vs. median = 0.70 [IQR: 0.62–0.83]; p = 0.012). The difference in the LnRHI between patients and controls was evident from hospitalization and persisted at two and six months without significant temporal changes. The proportion of COVID-19 patients with endothelial dysfunction (LnRHI ≤ 0.51) was 61% during hospitalization and 55% at six months. There was no significant difference in thrombotic or cardiovascular events, nor in mortality. This study demonstrates that COVID-19 adversely affects endothelial function, as evidenced by a reduction in the hyperemic vascular response index, and endothelial dysfunction may also persist.
