Unstable angina triggered by RSV infection in a patient with pre-existing CVD

Presentation, history and treatment
A 57-year-old male lorry driver, who was an ex-chronic smoker and had underlying chronic diseases, was hospitalized due to a 3-day history of fever, cough, and shortness of breath in April 2025.

The patient had multiple comor­bidities, including type 2 diabetes (T2D), dyslipidaemia, hypertension, and coronary artery disease (CAD), which were well controlled with em­pagliflozin 10 mg daily, metformin 1,000 mg BID, rosuvastatin 20 mg daily, losartan 100 mg daily and aspi­rin 80 mg daily.

Respiratory specimen from the patient tested positive for respiratory syncytial virus (RSV) and Haemoph­ilus influenzae on polymerase chain reaction assay. Chest X-ray revealed pneumonia in the left lower lobe of his lungs. (Figure) The patient was given symptomatic treatment, and his sec­ondary bacterial infection was treated with an antibiotic.

On day 2 of hospitalization, the patient began to experience short bouts of chest pain. Corresponding serial electrocardiography showed transient and reversible ST segment depression in leads V3 and V4. Se­rial troponin assay results were unre­markable. Subsequent CT coronary angiography showed stable CAD with moderate mid-left anterior descend­ing artery stenosis. The patient was diagnosed with unstable angina and managed with medical therapy.

Subsequently, the patient’s respi­ratory symptoms and fever gradually subsided, and he did not have recur­rence of chest pain. He was hospital­ized for 5 days and is currently in sta­ble condition. Chest X-ray 1 month later showed resolution of pneumo­nia. (Figure)

Discussion
Our patient with underlying CAD and other comorbidities was hospi­talized for severe RSV and H. influ­enzae infections as well as secondary bacterial infection. During this peri­od, he experienced unstable angina, likely induced by the heightened stress and inflammation caused by the two infections. Fortunately, with early medical attention and good control of underlying chronic diseas­es prior to the index hospitalization, he recovered quickly.

Recently published studies em­phasize the bidirectional relationship between chronic illnesses (eg, car­diovascular disease [CVD] and T2D) and respiratory viral infections (eg, influenza and RSV). Older age and comorbidities predispose patients to severe infections, which in turn lead to exacerbation of pre-existing CVD and/or underlying conditions, result­ing in acute complications, such as stroke or MI. This creates a vicious circle of deterioration and functional decline.^1-6

A retrospective US study found that 37 percent of patients hospi­talized with RSV experienced CV events during the high-risk period (of 1–28 days from admission), with congestive heart failure (CHF) being the most common event followed by atrial fibrillation and MI (25, 13 and 9 percent, respectively). Of these, 44 percent had no prior history of CAD. Furthermore, the risk of CV events re­mained elevated for at least 6 months following hospitalization.²

In Hong Kong, a territory-wide retrospective study in adults hospital­ized for RSV infection or influenza be­tween January 2016 and June 2023 found that patients with RSV infec­tion had significantly higher risks of inpatient mortality, severe respiratory failure, secondary bacterial pneumo­nia, and acute kidney injury vs those with influenza (p<0.001 for all). These results were consistent for patients aged ≥60, <60, and 50–59 years.⁴

A local public health impact study demonstrated a substantial burden of RSV infection and its sequelae. It is estimated that among 2,236,600 adults aged ≥60 years in Hong Kong, 65,159 symptomatic acute RSV in­fection cases would occur annu­ally, resulting in a projected annual economic burden of approximately HKD 569 million.⁷

Another modelling study on the same cohort found that compared with no vaccination, vaccinating 1,080,278 of these adults once with the recombinant adjuvanted RSV vaccine (RSVPreF3) would prevent 31,717 symptomatic RSV cases, 29,100 outpatient visits, 5,985 hos­pitalizations and 253 deaths over 3 years, assuming the same vaccina­tion coverage as for influenza in the same age group.⁸

Real-world observational studies among US adults aged ≥60 years (including those with immunocom­promising and underlying conditions, especially cardiopulmonary disease) have shown RSV vaccine effective­ness of 72–83 percent in the first season of use, providing significant public health benefit through reduced RSV-associated Accident & Emer­gency (A&E) visits, hospitalizations, and critical illness.⁹

RSV infection prevention and recommendations
The US Centers for Disease Con­trol and Prevention (CDC) Advisory Committee on Immunization Practic­es (ACIP) recommends a single dose of RSV vaccine in all adults aged ≥75 years, those aged 50–74 years with certain chronic medical conditions, moderate or severe immunocompro­mise, severe obesity, and those who may be at increased risk of severe RSV disease.^10,11

In Hong Kong, RSVPreF3 is approved for use in adults ≥60 years old to prevent RSV-related lower re­spiratory tract disease, and those 50– 59 years of age who are at increased risk of RSV disease.¹² According to the Centre of Health Protection’s Scientific Committee on Vaccine Pre­ventable Diseases, elderly persons (especially those aged ≥75 years or living in residential care homes) may receive RSV vaccination for personal protection, as an individual decision under informed consent in consulta­tion with their doctor.¹³

The latest European Society of Cardiology (ESC) clinical consensus statement advocates vaccination as a new form of CV prevention and acknowledges that “in an era of in­creasing recognition of prevention as crucial for reducing CVD burden, vaccinations could become a foun­dational pillar of preventive strat­egies alongside other established measures”.¹⁴

Severe RSV infection and as­sociated complications impact not only elderly individuals, but also in­dividuals with comorbid illnesses. Vaccination is an effective preventive measure against RSV-related mor­bidity and mortality. A multipronged approach is therefore needed to in­crease vaccination uptake among the elderly and the vulnerable. These measures include timely review and update of local scientific recommen­dations, educating doctors, increas­ing public awareness, and, ideally, a government-subsidized vaccination programme. While all doctors should participate in recommending vaccina­tion, a proactive approach by cardiol­ogists, specifically, will help maximize the beneficial effects of vaccination for high-risk populations.

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