A novel corona virus caused an outbreak of pneumonia in Wuhan (China) in December 2019. Since then the virus infected more than forty five million people and caused the death of more than one million patients.
Although the presence of the virus can be detected by an appropriate test, however we cannot screen for SARS-CoV-2 infection in the whole population. We do not know who are infected already, and who are the asymptomatic carriers of the virus. Consequently, we can only find and isolate those, who are having the highest chance to get infected and to develop more severe disease or death.
Based on the latest scientific data SARS-CoV-2 virus infected patients, who had severe complications or died, belonged to the older age groups, furthermore 46.4% had known co-morbidities (JAMA). According to a study published in the JAMA recently, patients who were hospitalised due to Covid-19 infection 31.2% had hypertension, 10.1% diabetes, 14.5% cardiovascular disease and 5.1% cerebrovascular diseases, respectively. Moreover, among those who required intensive care unit (ICU) management hypertension was present in 58.3%, cardiovascular disease in 25%, cerebrovascular disease in 16.7% (JAMA).
The atherosclerotic cardiovascular and cerebrovascular diseases, which together created a considerable proportion (19.6% or 41.7%* [*among those who required ICU]) of the reported co-morbidities during SARS-CoV-2 infection are very often asymptomatic. It can also be supposed that among the hypertensive subjects (31.2% or 58.3%* [*among those who required ICU] ) several patients might had asymptomatic atherosclerosis, as well. Moreover, patients with cardiovascular diseases have an increased risk of death due to COVID-19 (Lancet).
However, many patients, who are having macrovascular atherosclerosis are free from any clinical symptom even with advanced systemic vascular damages. The percentage of asymptomatic atherosclerosis assessed by carotid ultrasound was found to be 47% in apparently healthy middle age subjects with low Framingham Risk Score and with zero coronary artery calcium score (Mayo).
The SARS-CoV-2 virus infection’s gate is the ACE2 receptors. As a result of the ACE2 receptors activity angiotensin(1-7) is produced. While angiotension II (Ang II) has vasoconstrictive effect, angiotensin(1-7) has vasodilative action. Angiotensin(1-7) induces not only vasodilation but has anti-fibrotic, anti-inflammatoric and antiploriferative effects, as well (18-19 from Anguiano paper).
It is a plausible theory that the increased ACE2 receptor expression may cause enhanced vasodilation and if we could measure easily the peripheral vasodilation status, we may find the subjects with increased ACE2 level and increased risk for SARS-CoV-2 infection.
Scientific evidence proved the up-regulation of ACE2 as a compensatory response to different ischemic insults in different cardiovascular diseases. It seems that ACE2 counterbalances the vasoconstriction and other detrimental effects caused by angiotensin II, and the vasodilator ACE2 via Angiotension(1-7) may have cardio-protective effect (Anguiano). The ACE2 is elevated in heart failure and in left ventricular systolic dysfunction. Furthermore, in chronic kidney disease patients without previous history of cardiovascular disease, increased ACE2 level was found in case with asymptomatic atherosclerotic plaques. (Circulating angiotensin-converting enzyme 2 activity in patients with chronic kidney disease without previous history of cardiovascular disease. Nephrol. Dial. Transplant., 2015, 30, 1176-1185.). Anguiano.
Taking into consideration that the atherosclerosis is the most common basis of the cardiovascular diseases, revealing patients with subclinical atherosclerosis might play a significant role to find those subjects, who are at high risk for cardiovascular diseases, and thus for COVID-19 infection, as well.
If we could find the mentioned high-risk patient group, we could implement special actions among them, by which we may reduce their risk to be infected by SARS-CoV-2. These interventions might be their stricter isolation, higher vigilance towards them and, if we would have effective preventive medical therapy, we could start its early application.