College of Health and Life Sciences CHLS Hamad Bin Khalifa University Hamad Bin Khalifa University

The heart is the first organ to sense and give life and, as such, is the ultimate target of any internal or external challenge to the human body. Conversely, the cardiovascular system is at the heart of all events that our brain witnesses and records. Like the pandemics that came before, it is common sense and resilience rather than stubbornness that will ultimately determine our recovery from COVID-19. None more so than when it comes to these important, but ultimately fragile, bodily functions. 

From the early days of the outbreak China has accumulated evidence to suggest that  COVID-19 causes increased mortality and morbidity among individuals with a history of cardiovascular disease, diabetes, and asthma. To demonstrate this, Chinese scientists calculated the case fatality rate (CFR) for each condition, and published their findings in a recent edition of JAMA. They noted a 0.9% increase in individuals with no comorbidities, 10% for cardiovascular diseases (CVD), 7.3% for diabetes mellitus (DM), 6.3% for chronic obstructive pulmonary disease (COPD), and 6% for hypertension (HTN). 

In some respects, the above results are not particularly shocking. Previous studies show that Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) – which are, like COVID-19, coronaviruses – also increase morbidity among CVD sufferers. A more troubling finding is that individuals with cardiovascular diseases are particularly susceptible to the most severe form of COVID-19, which often leads to death. 

The association between CVD and higher rates of fatalities in pulmonary infections is directly related to the importance of the heart and related organs of the cardiovascular system to oxygen supplies. Blood is oxygenated in the lungs, which as we know is the primary target for COVID-19. Accordingly, a defective supply of oxygenated blood will directly affect blood vessels performance as well as the heart’s ability to cope with increasing demands on the body. 

In addition to the imposition of a “hypoxic condition” on a defective cardiovascular system, patients who suffer from heart failure would be unable to protect this organ from the infiltration of viral particles that cause myocarditis. This is an inflammation of the heart that, under normal conditions, requires intensive interventions. Finally, the increased inflammatory repertoire of circulated chemokines and other proteins like cardiac Troponin I, were seen as responsible for the induced-cell death of cardiac cells which also increased case fatality rates. 

Despite compelling evidence that a compromised cardiovascular system exacerbates the body’s efforts to defend itself against viruses, questions nevertheless remain as to why CVD patients are more susceptible to the most pernicious effects of COVID-19 than others. Is there a link, for example, between these findings and medications prescribed for CVD?

In an attempt to answer this and related questions, scientists are basing their analysis on the key-lock system by which viruses penetrate cells. This system depends on a key protein referred to as angiotensin-converting-enzyme type 2 (ACE2) which is normally present on the surface of the many cell types that make up our body, including the pulmonary and cardiovascular system. This protein is the path by which the viral particle “spike” unlocks human cells to pave the way for the entry of the virus.

Drugs commonly used for treating patients with CVD - especially those suffering from high blood pressure – are ACE-inhibitors, which are antagonists of ACE,the sister enzyme of ACE2. However, drugs which block the activity of ACE lead to increased expression of ACE2, which has numerous beneficial effects including lower blood pressure but also protection against acute lung injury caused by viruses like COVID-19. 

The American Heart Association, European Society for Cardiology and other international cardiovascular organizations recently urged against reducing the use of ACE inhibitors at this time. Put simply, there are no solid indications that COVID-19 will preferentially infect individuals taking these medications. Scientists and physicians also warn the public against making the personal decision to abruptly stop prescribed drugs. 

Individuals suffering from cardiovascular diseases should nevertheless be more cautious and abide strictly by the Center for Disease Control and Prevention (CDC) and World Health Organization (WHO) recommendations regarding COVID-19. Remember that those who care for you and your heart are professionals with experience and in-depth knowledge: they are giving their hearts to save ours. 

Georges Nemer is Professor of Genomics and Precision Medicine, and Coordinator of the Genetics and Translational Biomedicine Division at the College of Health and Life Sciences (CHLS) at Hamad Bin Khalifa University (HBKU).