July 29, 2021 https://doi.org/10.1016/ S0140-6736(21)00896-5
The Covid-19 pandemic is being caused by a single strand positive polarity RNA virus named Severe Acute Respiratory Syndrome Corona Virus 2 or SARS CoV-2. The official name was given on 11 February 2020 by the International Committee on Taxonomy of Viruses, and this was announced by the World Health Organisation the same day.
The first cluster of cases was identified in Wuhan, China, but since then almost 200 million cases have become infected by SARS CoV-2, and there have been more than 4 million (forty lakhs) deaths by this virus. India currently carries a burden of 32 million cases with 425000 deaths.
The initial impression had been that SARS CoV-2 only causes pneumonia bit soon it became apparent that there was a multi-system involvement. The virus attacks the lining of small blood vessels called capillaries, this is termed endotheliitis because the lining of blood vessels is named endothelium. Capillary wall inflammation results in multiple small blood clots (thrombi) that compromise blood flow to various organs. The inflammation of capillaries can be caused directly by SARS CoV-2 or by the immune/inflammation reaction it elicits. There are reports that the virus may similarly infect other organs apart from the lungs such as the heart, brain, kidneys, and liver.
There are reports of cardiovascular involvement and thrombotic complications with Covid 19. Infection and inflammation by SARS CoV 2 can increase the risk of heart attack (acute myocardial infarction or AMI) and ischemic stroke. A recent study from Sweden published in The Lancet has highlighted the enhanced risk of acute myocardial infarction and ischemic stroke.
We already know that there is a slight increase in the risk of acute myocardial infarction and stroke with flu, pneumonia, acute bronchitis, and other chest infections. Against this background, Swedish investigators investigated the association if any with Covid 19 and myocardial infarction or stroke. They looked at data from their registers for 86,742 Covid 19 patients with a median age of 48 years and 43% being males.
Two methods for the analysis of data were employed. In the first method, the cases served as their own controls, called the self-controlled case series (SCCS). Here incidence of myocardial infarction and stroke as compared with before and after a patient developed Covid 19 infection. Secondly, they compared the incidence of myocardial infarction and stroke with a comparable group of 348,481 matched controls. The matched controls were similar in age, sex, region along with adjustment for income, education, comorbid disease, and country of birth.
The risk of acute myocardial infarction was about three times higher in the first week after Covid 19, 2.5 times in the second week.
The risk of ischemic stroke was similarly increased by three times in the first week following Covid 19, and by 2.6 times in the second week.
Intriguingly there has been a decline in the cath lab for acute heart attack procedures by almost 30% across the globe. Cities in India too have recorded a reduction in the rate of primary percutaneous coronary intervention procedures (PPCI). The reasons for the observed decline in cases could be an actual reduction in the incidence of acute myocardial infarction brought about by staying indoors during lockdowns or delay in arrival to hospitals by patients with acute myocardial infarction. This delay could be the fear of contracting Covid 19 in hospital, a prospect that cannot be dismissed outright.
The Swedish study reports an increased risk of acute myocardial infarction and stroke soon after Covid 19, but this spike may not be big enough to make up for the lower rate of hospital admissions for heart attack. The Swedish study has estimated excess risk for acute myocardial infarction and stroke at around 0.02%, that is 1-2 cases per thousand.
The independent risk of suffering a heart attack or stroke with Covid 19, however small, cannot be taken casually. The Swedish study is the largest of this kind and hence the data presented is robust. The researchers have noted that the average incubation period is 5 days for Covid 19, and 98% of patients develop symptoms from 2 to 12 days of getting infected.
A study from Denmark has reported an increased risk of acute myocardial infarction following Covid 19 by 5 times, and raised risk of ischaemic stroke by ten times. Covid 19 is associated with a risk of atrial fibrillation that may in turn raise the rate of ischaemic stroke. The risk of stroke has been noted to be 7.6 higher with Covid 19 than with flu.
The higher risks of acute myocardial infarction and ischaemic stroke associated with Covid 19 infection are best explained by direct effects of the virus on endothelial cells and also the heightened inflammatory response that leads to greater coagulability of blood accompanied by exaggerated clumping of platelets. Long-term effects on the cardiovascular system remain to be ascertained.
Apart from the risk of increased ischemic cardiovascular events by Covid 19, there are also reports of direct inflammation of heart muscle termed myocarditis. Contrary to earlier reports, the incidence of myocarditis is low after Covid 19. Myocarditis is best assessed by cardiac MRI that can n to only reveal inflammation of heart muscle but also inflammation of the pericardium, which is the sac enveloping the heart. Again long-term effects of Covid 19 myocarditis are currently unknown because there has not been adequate time for follow-up.
Patients with myocarditis usually present with chest pain accompanied by ECG changes and increased troponin levels in the blood. A 2 D echocardiogram may demonstrate reduced contraction of the left ventricle. But cardiac MRI is best for a definite diagnosis short of endocardial biopsy that may be difficult in many cases, especially if mildly symptomatic. Autopsy series have shown a very low incidence of myocarditis, but these are very sick patients who have died because of Covid 19. Usually, Covid 19 presents with minimal or no symptoms. All heart associations recommend that a sportsperson with confirmed myocarditis should resume training after 3-6 months of symptom onset under the supervision of a physician.
So how does one prevent heart attack during the current pandemic? Firstly one must avoid infection by SARS CoV 2. This is best done by wearing a mask, maintaining distance, and ensuring proper etiquette during coughing or sneezing. Hand washing will also help. Vaccines have been found to be effective in preventing severe disease, hospitalization, and death.
Along with the above, the usual lifestyle adoption is required to prevent cardiovascular disease. Firstly some form of exercise for as little as 20 minutes in a day will go a long way in reducing weight, lowering blood pressure and blood sugar. This could be in the form of a brisk walk, a jog or even a game of badminton. Exercise becomes of paramount importance amid frequent lockdowns that corral up the public.
Blood pressure must be kept in check and optimal blood sugar should be maintained if a person is suffering from diabetes. A healthy low oil largely vegetarian diet cannot be over-emphasized. Crucially, it is imperative that if symptoms of chest discomfort, palpitations, or breathlessness develop a doctor is speedily consulted.
An acute heart attack if not treated quickly can be catastrophic. Nearly 25% of acute heart attack patients die within 30 minutes of onset. There is undoubtedly a credible fear of contracting Covid 19 on visiting a hospital but this must be tempered with the knowledge that an acute heart attack if left untreated could lead to death.
In conclusion, the risk of increased incidence of acute heart attack and ischemic stroke is clear and present in the current pandemic. Covid 19 by itself can directly cause cardiovascular events causing immediate challenges and also for the future. A sedentary lifestyle coupled with the fear of visiting a hospital despite symptoms shall most certainly amplify problems of cardiovascular morbidity and mortality. Tradeoffs are a part and parcel of life and also clinical medicine, we are constantly balancing benefit with risk.