Level of the SARS-CoV-2 receptor ACE2 activity is highly elevated in old-aged patients with aortic stenosis: implications for ACE2 as a biomarker for the severity of COVID-19

Coronavirus disease 2019 (COVID-19) has a high mortality in elderly patients with pre-existing cardiovascular diseases. The cellular receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the angiotensin-converting enzyme 2 (ACE2), thereby implicating a link between cardiovascular diseases and SARS-CoV-2 susceptibility. Aortic stenosis (AS) represents a chronic inflammatory state with severe cardiovascular complications in the elderly, a prime condition for COVID-19 mortality. The circulating ACE2 levels were measured in 111 patients with severe AS and compared to patients with hypertension and healthy individuals. About 4 times higher circulating ACE2 activity was found in patients with severe AS than in hypertensives or healthy individuals (88.3 ± 61.6., n = 111, 20.6 ± 13.4, n = 540, and 16.1 ± 7.4 mU/L, n = 46, respectively). Patients with severe AS were older than patients with hypertension (80 ± 6 years vs. 60 ± 15 years, P