Applying the Lessons of Influenza to COVID-19 During a Time of Uncertainty
Authors: Orly Vardeny, Mohammad Madjid, Scott D. Solomon
Journal: Circulation (2020)

the 3 of us were consulted by the American College of Cardiology to assist in developing expert guidance to inform our colleagues regarding potential cardiac implications of a novel coronavirus epidemic in Wuhan, China, now known as coronavirus disease 2019 (COVID-19).We are not infectious disease experts, nor do we have specific expertise in coronaviruses, but we have been studying the effects of influenza on the cardiovascular system and investigating ways to lower the risk of influenza-related complications in our high-risk patients.As information emerges from this new pandemic, it is becoming abundantly clear that, as is the case with influenza, patients with cardiovascular disease are especially vulnerable to the ravages of this virus, which may have unique effects on the cardiovascular system.The lessons we have learned from influenza and past coronavirus outbreaks can be especially informative during this time of limited evidence on this new threat.The association between viral respiratory illness and risk for subsequent cardiovascular events has been well established; acute infections, particularly influenza, have been linked temporally to subsequent myocardial infarction and heart failure decompensation. 1,2Viral infection increases metabolic demand, which can unduly decompensate individuals with heart failure who have limited reserve.Some viral infections, such as influenza or coxsackie, have direct toxic effects on the myocardium and can cause myocarditis.Influenza has been associated with destabilization of atherosclerotic plaques, leading to acute coronary syndrome, and higher rates of ventricular arrhythmias.The extent to which, and mechanisms by which, coronaviruses may contribute to increased cardiovascular risk in the general population or in high-risk individuals remains unclear, but early reports suggest that an individual's risk, including for death, is directly related to his or her degree of comorbidity.Among 72 314 patients in Wuhan (of whom 44 672 had laboratory-confirmed COVID-19), the case-fatality rate was 10.5% among those with underlying cardiovascular disease and confirmed infection, compared with 2.3% in the cohort overall. 3Whereas the exact mortality rates of this disease have been difficult to assess accurately, may vary regionally, and may be lower than originally estimated given limited testing and unknown number of asymptomatic cases, there is almost certainly a multifold increased relative risk associated with preexisting cardiovascular disease, a finding that is consistent with the Middle East Respiratory Syndrome experience.Chronic conditions influencing severity of illness for coronaviruses are analogous to factors influencing risk related to other respiratory viruses, including seasonal influenza.Older adults and those with multiple medical conditions are more susceptible to infection-related complications because of a less robust immune system and are more likely to develop secondary bacterial infections.Shared pathogenic mechanisms between cardiovascular disorders and infectious diseases include endothelial