People with diabetes are overrepresented among those with potentially life-threatening respiratory infections including severe RSV, while 30% of people who reach ICU with respiratory infections have diabetes as a comorbidity.
With peak respiratory virus season upon us, four experts discuss how and why RSV affects heart disease—and vice versa.
Epidemiological and hospital-based surveillance figures show respiratory viral diseases, including influenza and COVID, are associated with acute cardiovascular disease and increased mortality.
Similarly, acute RSV presentations can exacerbate underlying disease (including respiratory, cardiac and cerebrovascular diseases) and increase mortality risk, says Professor Dominic Dwyer, infectious diseases specialist from Westmead Hospital.
“Every winter when we have the flu season or the RSV season, we see an increase in other causes of death,” he says. “And that’s not necessarily directly related to the acute infection, but often in the month or two after that acute infection. So there’s two things we need to target: the acute infection and the longer-term complications of an acute infection.”
There is also an increased risk of adverse effects in people who are otherwise healthy but getting older, he adds.
Geriatrician Dr Desmond Graham from Northern Beaches Hospital notes ageing increases risk of frailty and comorbidities such as diabetes, heart failure, and cognitive impairments, which makes people vulnerable to acute stresses.
“And then you just need something to tip you over the edge to create this cascade event that occurs,” he says. “It’s like a snowball that’s picking up steam downhill. So if you get RSV, it’s almost a catalyst for all those grumbling, underlying comorbidities to come to the forefront.”
Cardiologist Dr Andrew Sindone says 25% of hospitalised adults aged 50 or older with RSV infection will experience an acute cardiac event.
“They get heart failure most commonly, but also myocardial infarction and stroke, and one in 12 patients with no previously diagnosed cardiovascular disease end up with these problems,” he says.
“People didn’t put that together for a long time, but the risk of severe outcomes was nearly twice as high in patients with acute cardiac events compared to those who didn’t have an acute cardiac event if they have RSV.”
Increased risk is particularly high in the first week, but persists for a month post-discharge, so it is important to educate patients and family members about the ongoing risk of adverse events after the acute period.
The inflammatory response is largely responsible, says Professor Dwyer, with inflammatory stress being significant in cases of acute illness that necessitate hospitalisation.
As a respiratory-specific (rather than systemic) infection, RSV places a load on respiratory function and can also compromise the cardiac system.
Pneumococcal disease and pneumococcal pneumonia, or other forms of bacterial pneumonia, can further complicate respiratory virus infection, he adds, and they in turn can cause cardiac disease.
Dr Sindone says data shows RSV infection leads to elevated levels of interleukin-1, interleukin-6, and CRP, “which all lead to increased blood viscosity, increased blood coagulability, and also a significantly increased risk of plaque rupture.”
“Those are all things that can cause an acute myocardial infarction and lead someone to end up in coronary care,” he says.
The virus makes circulation more dynamic and puts an increased load on the heart, he adds, which may impact people with heart failure.
“If the heart is already working at the top of its Frank-Starling curve, then people do get decompensation,” Dr Sindone says.
People with type 2 diabetes are particularly at risk of infections, including RSV, and of adverse cardiovascular events related to them, says endocrinologist Professor Ted Wu, Director of the Royal Prince Alfred Hospital Diabetes Centre.
“There is an effect of diabetes on the immune system. It’s not just about blood glucose, although at higher blood glucose, there’s perhaps more of an effect on the immune system. However, it’s the general inflammatory cascades that are disrupted in diabetes that may alter the body’s susceptibility to infections.”
People with diabetes and cardiovascular disease are also more vulnerable to the effects of an infection such as RSV, he says.
“For a little while after the big COVID waves, we saw huge numbers of presentations of new diabetes. I’ve actually just seen data supporting that with RSV as well, that if you get an RSV infection, two thirds of people had worsening blood glucose control, the HPA1C went up and their diabetes control got worse because of the RSV.”
RSV can also push people from the pre-diabetic to the diabetic stage, he adds.
“I think it bears remembering that diabetes is a spectrum. You don’t go from normal to diabetes in one day…it only takes something like an RSV infections to push people from the pre-diabetic stage to the diabetic stage.”
Preliminary data about vaccination is encouraging.
“We’ve only had the RSV vaccine for a couple of years… but the data seems to be very good, particularly in reducing cardiovascular events and reducing heart failure hospitalisation. So that may improve the cost effectiveness and also may lead to downstream benefits in reducing myocardial infarction, stroke and mortality in people who get RSV infection,” Dr Sindone says.
Vaccination against respiratory infections is also improving outcomes in aged care by allowing a more proactive approach, Dr Graham says.
“We can now manage and keep people in aged care facilities for longer, which means they don’t need hospital admissions, which ultimately leads to better health outcomes overall,” he says.
The Department of Health and Aged Care recommends RSV vaccination for:
Dr Sindone says international guidelines recommend vaccination against COVID, RSV, influenza, pneumococcus and shingles in people with preexisting disease to help prevent exacerbations of heart failure and hospitalisations and reduce mortality.
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