Delhi has been seeing an unprecedented spike in cases of swine flu this year, recording around 1,777 confirmed cases so far. This is nearly six times the tally of around 229 recorded in the same period last year Delhi has been seeing an unprecedented spike in cases of swine flu this year, recording around 1,777 confirmed cases so far. This is nearly six times the tally of around 229 recorded in the same...
Delhi has been seeing an unprecedented spike in cases of swine flu this year, recording around 1,777 confirmed cases so far. This is nearly six times the tally of around 229 recorded in the same period last year. Amid the surge in cases, doctors have flagged the effects the disease has beyond lungs, and how it can affect the heart.
The H1N1 virus, commonly known as swine flu, is a type of influenza virus and primarily a respiratory illness, which attacks the nose, throat and lungs. Dr Gautam Naik, a senior cardiologist at Indraprastha Apollo Hospital, Delhi, tells Tabshir Shams that its reach, however, often extends well beyond the chest cavity. He also warned that patients with cardiac risk factors need to be paying closer attention than they currently are.
Influenza can have significant effects on the cardiovascular system. The infection triggers a systemic inflammatory response, raises heart rate, and increases the body’s metabolic demand — all of which place added stress on the heart.
In patients who already have coronary artery disease, this inflammation can destabilise cholesterol plaques inside blood vessels. This can increase the risk of heart attack. Fever, dehydration, low oxygen levels and a racing heart rate can independently push a weakened heart toward failure.
In rarer cases, the virus can cause myocarditis, which is inflammation of the heart muscle itself. This can impair the heart’s pumping ability and produce dangerous rhythm disturbances.
The major cardiac risks tied to influenza infection include acute coronary syndrome or heart attack, worsening of existing heart failure, new-onset heart failure, and serious rhythm disturbances. Myocarditis and pericarditis, while less common, remain a serious concern.
While research shows that the risk of a heart attack rises sharply in the days immediately following an influenza infection, the virus effectively acts as a trigger in people who already carry underlying cardiovascular vulnerability, rather than causing harm in isolation.
Cardiac symptoms during a flu infection are frequently mistaken for the flu itself. Patients must not ignore new or persistent chest pain or pressure, breathlessness disproportionate to their respiratory symptoms, and new palpitations or rapid and irregular heartbeat. The same goes for fainting or severe dizziness, unexplained sweating, increasing leg swelling, or a sudden worsening of breathlessness. This is particularly relevant for those with existing heart conditions.
Chest discomfort, accompanied by sweating, nausea, or pain radiating to the arm, shoulder, back or jaw should be treated as a potential cardiac emergency.
The danger is highest among those with pre-existing heart disease, diabetes, hypertension or other risk factors. However, young people with no cardiac history are not entirely immune. Viral infections like influenza can, on rare occasions, cause myocarditis even in a previously healthy heart. Persistent chest discomfort, unexplained breathlessness, palpitations, fainting, or a marked drop in exercise capacity after a bout of flu should prompt medical evaluation, regardless of age.
The reassuring part is that the vast majority of otherwise healthy young people recover fully, with no lasting cardiac damage.
— For most people who recover from an uncomplicated flu, there’s no reason to assume any permanent heart damage has occurred. The exception is patients whose infection led to myocarditis, a heart attack, significant arrhythmia or heart failure. These patients may need structured cardiac follow-up since recovery of heart function can take time, and in some cases, dysfunction can persist.
Tabshir Shams covers health for The Indian Express. He holds a Master's degree in International Relations from South Asian University. Before joining The Indian Express, he interned at The Hindu from December 2025 to June 2026, where he assisted in the research and editing of a book on delimitation published by The Hindu Group Publications. During this time, he also wrote for The Hindu's Text & Context section, on subjects ranging from Pakistan's military establishment to Bangladesh's elections, and reported a Spotlight feature on a jute mill in Samastipur and its ripple effects on labour migration and the local economy. In July 2025, he interned at The Indian Express, where he wrote several explainers on international relations alongside a health report. His Master's thesis examines civil-military relations in Pakistan, with a focus on the post-2019 period. ... Read More