How cold weather affects your heart

Now that the clocks have gone back and the temperature is falling, it is worth knowing that winter is not only harder on the chest and the joints. It is harder on the heart. The British Heart Foundation puts it plainly. Heart attacks are more common in winter, and the reasons are well understood.

The effect does not wait for snow and ice, either. Official figures on extra winter deaths in the UK suggest the rise in risk begins once the average temperature drops below 12°C, a threshold reached well before the first frost.

What the Cold Does to Your Circulation

When you get cold, your body's first priority is to keep its core warm. To do that, blood vessels in the skin, fingers and toes narrow so that less heat is lost. This is called vasoconstriction, and it is a perfectly normal response.

The cost is extra pressure in the rest of the circulation. Your blood pressure rises, your heart rate rises, and your heart has to work harder to pump blood around the body. For a healthy heart that is easily managed. For a heart already under strain, from narrowed arteries, high blood pressure or a weakened pumping action, the extra strain can bring on symptoms, especially during exercise.

Cold weather can also make the blood thicker and stickier, which in rare cases can lead to clots, and that raises the risk of a heart attack or stroke. How high blood pressure affects the heart explains why a sustained rise in pressure matters over time.

What the Research Shows

BHF funded researchers at the University of Bristol and University College London looked at records of people over 60 in the UK, Ireland and the Netherlands. They found that heart attacks and strokes were more than twice as likely during cold spells lasting at least four days. The biggest factor seemed to be a fall in temperature compared with the days before, rather than exactly how cold it was. In other words, a sharp drop matters, not only the coldest days.

The effects also linger. Researchers have shown that the impact of a cold day or a cold spell on health can be seen for two weeks or more afterwards.

A further BHF funded study looked at how risk factors change with the temperature. On average, the lower the temperature, the higher people's cholesterol and blood pressure and the lower their vitamin D. The researchers thought this was probably less about the cold itself and more about how behaviour changes when the weather turns. They also found that the risk of dying of heart disease in a cold snap was higher in people who drank more than one alcoholic drink a week or had ever smoked.

Who Needs to Take Most Care

Everyone's heart responds to the cold, but some people feel the effect far more than others.

• People with angina. Symptoms can be worse or happen more often in cold weather, and some people find they are less able to be active when it is cold.
• People with coronary artery disease. A BHF funded study at King's College London found that breathing cold air reduced blood flow in the coronary arteries of people whose arteries were blocked, while in people with chest pain but no blockages it increased. It was a small study, but it helps explain why cold air and exertion together can be a problem.
• People with heart failure or another long term heart condition. The NHS recommends the annual flu vaccine for people with heart conditions such as coronary heart disease or heart failure, because of the extra risk winter infections carry.
• Older adults. The studies above were in people over 60, and age raises cardiovascular risk on its own.

Protecting Your Heart Through Winter

Most of what helps is simple, and the British Heart Foundation's advice for cold weather is practical rather than medical.

• Keep your main room warm. Aim to heat the room where you spend most of your time to at least 18°C.
• Layer up. Several thin layers trap heat better than one thick one, and a hat, scarf and gloves help keep you warm outdoors.
• Breathe warmer air. If you have angina, a scarf wrapped loosely around your mouth and nose, or a face mask, means you breathe in warmer air, which may help limit symptoms.
• Keep moving indoors. On particularly cold days, exercising indoors rather than outside is sensible if you have a heart or breathing problem. Which types of exercise are best for your heart has ideas worth adapting for home.
• Eat warm, filling meals and have hot drinks through the day.
• Keep a stock of your medicines, so a spell of bad weather never leaves you without them.
• Get vaccinated. The NHS offers a free flu vaccine to adults with heart conditions such as coronary heart disease or heart failure, and to everyone aged 65 or over.

The habits that matter all year still matter here. The research linking cold snaps to higher risk in people who drink or smoke suggests that cutting back on alcohol and stopping smoking protect the heart in winter as well as over the long term.

Know the Signs of a Heart Attack

Because heart attacks are more common in winter, it is worth being sure of the signs. The NHS lists symptoms of a heart attack including chest pain that may feel like crushing or squeezing and may spread to the arm, neck and jaw, shortness of breath, feeling or being sick, a feeling like indigestion, and pale, blue or grey skin. If you think you or someone else is having a heart attack, call 999 straight away, and do not drive yourself to A&E.

Our pages on heart attack and chest pain explain these warning signs in more detail.

A Good Time for a Check

Winter is also a sensible point to take stock. If your usual pattern of chest pain has changed, coming on with less effort than before, at rest, or more often, that needs same day medical assessment rather than a routine appointment. Other changes are worth acting on rather than putting down to the season, such as becoming breathless doing less than you could a year ago, or home blood pressure readings that have crept up.

We have a specialist interest in cardiovascular prevention, and a prevention appointment looks at blood pressure, cholesterol and family history together. Where blood pressure readings are uncertain, a 24 hour blood pressure monitor records measurements through the day and night rather than relying on a single reading in a clinic.

Conclusion

Cold weather makes the heart work harder. It narrows the blood vessels near the skin, raises blood pressure and heart rate, and can make the blood more likely to clot, which is why heart attacks are more common in winter. The risk begins to climb well before the first frost, and a sudden drop in temperature appears to matter more than exactly how cold it gets.

Most of the protection is simple. Keep warm at home, dress in layers, stay active indoors on the coldest days, keep your medicines stocked and get vaccinated if you are eligible. If you have angina, heart failure or another heart condition, take particular care, and do not dismiss new or worsening symptoms as just the weather.

If you have a heart condition and would like advice before winter sets in, or you have noticed new symptoms as the weather has turned colder, you can contact us at Kingston Cardiologist to arrange a cardiology consultation in Kingston upon Thames or central London. Appointments are available in person and virtually, with blood pressure monitoring and other tests arranged where they are needed.