The Effect of Hot and Cold Weather on Heart Patients

In our heart patients, seasonal transitions and extreme weather conditions are associated with a visible increase in hospital presentations. In this article I will explain the effect of hot and cold weather on the heart.

Cold Weather and Vessel Constriction (Spasm)

Cold weather causes the vessels under the skin to constrict (vasoconstriction) in order to preserve body temperature; this raises blood pressure and increases the effort the heart spends to pump blood. Large population studies show that presentations with heart attack and stroke increase markedly in the winter months compared with the summer months; this risk rises especially when cold is combined with sudden physical exertion (such as shovelling snow).

Extreme Heat, Fluid Loss and Low Blood Pressure

In extremely hot weather, on the other hand, the body dilates the vessels to balance its temperature and loses fluid through sweating; this can lead to low blood pressure, an increase in heart rate and, if enough fluid is not taken, an extra burden on the heart. Especially in our elderly patients taking blood pressure medication, the dose may need to be reviewed temporarily during extreme heat.

Precautions to Take in Winter and Summer

In the winter months we recommend that you avoid sudden and intense physical exertion (especially in the cold) and dress in layers when going outside. In the summer months we recommend avoiding heavy physical activity during the hottest hours of the day, drinking plenty of fluids and, if you use blood pressure medication, we place importance on regular blood pressure monitoring.

Frequently Asked Questions

Does the risk of a heart attack really increase in the winter months? Yes; large-scale studies clearly demonstrate this seasonal increase; the combination of cold weather and sudden exertion is particularly risky.

Should I reduce my blood pressure medication in the summer months? We recommend that you do not make this decision on your own, but always consult your doctor.

Which weather condition is riskier, hot or cold? Both create risk through different mechanisms; cold acts through blood pressure and vessel constriction, while heat acts through fluid loss and low blood pressure.

Conclusion

Extremely hot and cold weather conditions have different but real effects on the heart. Simple precautions appropriate to the season can considerably reduce this risk.

You can book an appointment for an assessment of your seasonal risk factors and your medication doses.

References

1. Stewart S, Keates AK, Redfern A, McMurray JJV. Seasonal Variations in Cardiovascular Disease. Nat Rev Cardiol. 2017;14(11):654-664.