SHARES
Data from the current Covid-19 pandemic show mortality is higher among those above 60 and in patients who have underlying health conditions such as heart disease and diabetes.
Recent studies do highlight the possible link in patients between high blood pressure and a poorer outcome with COVID-19 infection.
In particular, researchers notice higher death rates are seen in COVID-19 patients with existing high blood pressure or taking blood pressure-reducing medication. You may ask what is the connection? From here, how can we manage risks better?
Connection between Hypertension and COVID-19 Infection
Recent studies by Baric and other researchers point towards the spread of COVID-19 infection between bat population through multiple ACE2 receptors. The coronavirus attaches itself to the protein found on cell surface receptors (called ACE2 receptors) and invades into the cell.
Coincidentally, these ACE2 receptors are also found on cells in the human lungs, intestine, kidney and blood vessels. Usually, it takes multiple generations of mutations for a virus to move form its original host species (in this case, the bats), to another species such as humans. As the virus mutates, it can change from relatively benign infection into something capable of causing a pandemic.
As such, therein is the connection in people with hypertension, the ACE2 receptors. People with high blood pressure usually have more active Renin-Angiotensin-Aldosterone System (RAAS). These hormones are the cause behind why your blood pressure shoots up, or your heart beating fast and even developing diabetes.
In response, our lungs produce more enzymes, called Angiotensin Converting Enzyme 2 (ACE2) in receptors, to block the activity of Angiotensin Converting Enzyme, ACE. This is achieved by ACE2 breaking down excess Angiotensin II. These receptors are the potential entry points for coronavirus COVID-19 infection
Covid-19 (SARS-CoV-2) virus infecting cell through ACE-2 receptor. [3]
Does High Blood Pressure Mean a Higher Risk for COVID-19 Infection?
Theoretically it is possible that people with more ACE2 receptors in lungs, such as those with high blood pressure, provide a greater chance for coronavirus SARS-CoV-2 to invade the body cells. However, there is still not enough evidence to conclude on this. Moreover there are inconsistent observations that do not support this theory.
In fact, the ACE2 receptor is also found on sex chromosome, where women express this protein more than men. However, on the contrary, we are seeing that COVID-19 is affecting more men than women.
Moreover, ACE2 expression decreases with age. Yet, we are also seeing that COVID-19 affect more people of advanced age.
In short, current observations are counter-intuitive to this theory. There is no conclusive evidence on higher chance of coronavirus infection in people with high blood pressure. Likewise, for elderly patients with more severe COVID-19 infection, there is still a possibility that high blood pressure may be over-represented among this group of people.
Having said so, past studies during SARS outbreak in 2013 yield inconclusive results on the use of medication that binds to ACE2 receptor to prevent SARS infection. Therefore, further research in this area can give more insight and may even lead to effective treatment.
Does High Blood Pressure Medication Affect Outcome for COVID-19 Infection?
Common blood pressure-lowering medications are Angiotensin Converting Enzyme inhibitor (ACE-i) and Angiotensin Receptor Blocker (ARB). In this regard, ACE-i/ARB can actually increase the expression of ACE2 receptors.
There is currently no evidence of a worse COVID-19 outcome in connection to ACE-i/ARB use. Meanwhile, researchers are tapping into the question with more preclinical studies while doctors are keeping a watchful eye and carefully considering the best treatment plan.
In spite of that, ACE2 does play a protective role in the lungs against condition like influenza-induced acute respiratory distress syndrome. In this sense, a lack of ACE2 in elderly people may be a reason for overwhelming COVID-19 infection.
Photo by The National Guard from Flickr
Conclusion
Studies are pointing towards the link between COVID-19 infection and high blood pressure. However, the underlying mechanism is still not entirely clear. It is hard to apply knowledge to clinical benefits at this point in time. Further research may clear up the phenomenon and help improve the outcomes of COVID-19 patients.
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References:
1. Baric R. Is there a high blood pressure and coronavirus link [Internet]? WebMD LLC. 2020. (Available from: https://www.medicinenet.com/script/main/art.asp?articlekey=229079; last updated on 2020 Mar 21; last accessed on 2020 Apr 7)
2. Feng L, Karakiulakis G, Roth M. Are patients with hypertension and diabetes mellitus at increased risk for COVID-19 infection? The Lancet. 2020 Mar 11; 8(4):PE21. DOI:https://doi.org/10.1016/S2213-2600(20)30116-8
3. Firas AR, Mazhar SA, Ghena AK, Dunia MS, Amjad DA. SARS-CoV-2 and coronavirus disease 2019: what we know so far. Pathogens. 2020;9(3):231. DOI: https://doi.org/10.3390/pathogens9030231
by Chang Xian
View all articles by Chang Xian.
