COVID-19 and the peculiar case of the missing myocardial infarction

In recent months, the COVID-19 pandemic has swept across the world, overwhelming hospitals in all corners of the globe, with China, the United States of America, Italy, India, Brazil, and South Africa among the worst hit. Amongst the chaos in many of these hospitals, cardiology teams found the number of people receiving emergency treatment for myocardial infarction (MI) and other cardiovascular conditions was strangely plummeting.[1] Even in areas where COVID-19 has been seemingly well-controlled, such as Australia, the same phenomenon has been noted. [2]

In May, the Spanish Society of Cardiology published a preliminary publication which estimated that levels of Percutaneous Coronary Intervention (PCI ) procedures for ST-elevated myocardial infarction (STEMI) during the pandemic were down as much as 40% from pre-pandemic levels across Spain.[3] In Northern California, the weekly rates of hospitalisation for acute MI decreased by up to 48% during the COVID-19 period. [4] Further, a 38% decrease in primary percutaneous coronary interventions (PPCI), the American College of Cardiology recommended standard treatment of STEMI patients, has been observed in US catheterization laboratories.[5] Admissions for acute MI were significantly reduced during the COVID-19 pandemic across Italy; in one study daily hospital admissions for acute coronary syndrome (ACS) (which includes STEMI, Non-STEMI (NSTEMI) and unstable angina) decreased from 18.0 in the pre-COVID-19 control period to 13.3 in the COVID-19 period,[6] another found a 48.4% reduction in MI presentation across different centers.[7]

WHAT UNDERLIES THIS PHENOMENON?

Most concerningly, according to interventional cardiologist Associate Professor Dion Stub, is the “real possibility that patients are avoiding coming to hospital… [and] are potentially afraid even to see their GP”.[8] If this is the case, it suggests that the COVID-19 pandemic has resulted in a fear of face-to-face medical care. With people more likely to overlook symptoms and remain at home, it would follow that, when they do seek help, it is likely to be when their condition is far more critical. This hypothesis is supported by observations from the Queen Mary Hospital in Hong Kong that, during the COVID-19 pandemic, patients have been presenting to the hospital late in the course of heart attacks, when treatment is far less effective.[9] In the aforementioned latter Italian study, there was an accompanying rise in STEMI case fatality rate compared with the same 2019 period and a parallel increase in complications was also registered.[7]

A similar phenomenon was observed during the 2003 SARS epidemic, where a study found almost two thirds of lung cancer patients were afraid of visiting the Taipei Veterans General Hospital in Taiwan during the outbreak, while more than a third felt SARS was more dangerous than their cancer.[10] Although it must be noted that patient behaviour may be altered if they believe they are more susceptible to complications of respiratory disease due to pre-existing lung cancer, the patient sentiment captured by this study is pertinent to the current outbreak.

It is important to consider other possible explanations for the reduced cardiac presentations. In the age of social distancing, human behaviours, such as social interaction, diet, sleep, and physical activity have been considerably modified. It is possible that some of the risk factors for MI, like high-cholesterol diets, excessive alcohol consumption, or lack of physical exercise, have been removed. Although this cannot be excluded as a contributing factor to the dramatic changes being observed across the world, it seems an unlikely explanation, especially since data from activity tracker users has demonstrated a significant decline in steps taken during COVID-19. [11]

WHY IS THIS IS SO PERPLEXING?

Since respiratory infections typically increase the risk of MIs, it would follow that a higher incidence of emergency cardiac presentations should be observed.[12] Indeed, the influenza vaccine is a key

intervention to prevent against MI.[13] The risk of increased MI follows shortly after the development of respiratory infection, so a rise in heart attacks should correlate strongly with increased respiratory illness; however, this has not been the case.

Further, psychosocial stress, often associated with depression and anxiety, is a strong independent risk factor for adverse cardiovascular events; the mind-heart connection likely accounts for a substantial portion of the attributable risk.[14] Thus, with the significant mental health burden resulting from the COVID-19 pandemic and associated lockdowns,[15] it stands to reason that there would be an accompanying increase in MIs. COVID-19 can have a direct cardiotoxic effect, which should be increasing the number of patients presenting with heart problems.[16]

Whilst we remain in the midst of the global COVID-19 pandemic, it is hard to draw causality and understand the full picture of this intriguing occurrence. There are ongoing studies to provide more clarity to these findings and to ascertain the underlying reasons for decreased emergency cardiovascular presentations at hospitals across the globe. Further, a number of publications have emerged describing similar declines in presentations to emergency for stroke,[17] or mental health emergencies,[18] among other conditions. Evidently, this phenomenon is not limited to cardiac problems.

In the interim, there is an important message to convey to patients: don’t delay seeking help. Professor Garry Jennings, Senior Director at the Baker Heart and Diabetes Research Institute, recently wrote in the Medical Journal of Australia about his worry that ‘some people with heart disease are abandoning the usual medical advice at a time when they may need it the most’.[19] There is a very real risk, especially in Australia, that despite being successful in minimising the effect of COVID-19 on our health system so far, we risk seeing an increase in deaths from preventable illnesses in the coming months.

As the global community continues to fight COVID-19, it is crucial to combat the perception that people must stay away from hospitals or that hospitals are not safe places to seek treatment. The pandemic toll will be much worse if it leads people to avoid care for life-threatening, yet treatable, conditions.

Jeremy Hunt is a first year medical student at the University of Queensland, who majored in computer and biomedical sciences as part of his undergraduate BSc. Within the global and public health spheres, Jeremy is interested in the interplay between business, legislation and medicine and has consulted on projects for international health non-for-profits.

jeremy.hunt@uq.net.au

None

None declared

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