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The Invisible Summer Strain: How Heat Impacts Your Heart
Heat is more than just uncomfortable. It can place significant stress on the heart. In a hot,
humid climate like Singapore, the link between rising temperatures and cardiovascular
health is becoming increasingly important.
A hidden but serious risk
There is a well-established link between prolonged heat exposure and cardiovascular events. In Singapore, 70 to 120 people are admitted to hospitals each year for serious heat related illnesses. More concerningly, research has found that even a small temperature rise can have a measurable impact on heart health. Studies have shown that for every 1°C increase in average temperature, the risk of sudden cardiac arrest can rise by 6–7%.
Globally, similar patterns have been observed. Heat stress has been linked to increased cases of heart attacks, unstable angina and sudden cardiac events. In Singapore alone, there are more than 3,000 sudden cardiac arrests each year and environmental stressors
like heat may act as a trigger.
Not just a risk for heart patients
A common misconception is that only people with known heart disease are at risk. In reality, about half of sudden cardiac arrest cases in Singapore occur in individuals with no prior diagnosis of cardiovascular disease.
Many may have underlying risk factors or undetected conditions that only surface under physical or environmental stress. At the same time, those with existing heart conditions remain especially vulnerable, as their hearts are already under strain.
Warning signs not to ignore
When the body is exposed to excessive heat, the heart works harder, with increased overall workload. This can lead to symptoms such as:
❤ Palpitations
❤ Excessive sweating
❤ Fainting
❤ Shortness of breath
❤ Dizziness or light-headedness
❤ Fatigue
❤ Chest pain
❤ Confusion
These symptoms should not be dismissed. Early action is critical.
If someone is experiencing heat stress:
❤ Stop the activity immediately
❤ Move to a cooler environment (preferably indoors)
❤ Begin rapid cooling — remove excess clothing, use water or fans to promote evaporation or apply ice/cooling packs
❤ Seek medical attention promptly, especially if symptoms persist
Protecting your heart in the heat
Heat-related risks can be reduced with simple precautions:
❤ Drink fluids regularly, even if you’re not thirsty.
❤ Dress for the weather. Wear light, breathable clothing.
❤ Avoid strenuous exercise during peak heat hours.
❤ Ensure proper recovery before and after physical activity.
❤ Build tolerance gradually by increasing intensity slowly and avoiding
sudden high exertion.
❤ Exercise with a buddy, so someone can assist if symptoms arise.
❤ Follow work-rest cycles, especially for those working outdoors.
❤ Before you start any endurance activities like marathons, go for a medical
check-up and screening.
When every minute counts
Heat-related cardiovascular stress is a time-sensitive condition. The earlier the intervention, the better the outcome. Rapid cooling and heat removal are critical first steps.
For individuals with known heart disease, the risks are even higher. In severe cases such as cardiac arrest, the early application of Cardiopulmonary Resuscitation (CPR) and use of an Automated External Defibrillator (AED) can be life-saving to help save a life.
As temperatures rise, so does the strain on your heart — often in ways you cannot see or feel immediately. Whether you are exercising, working outdoors or simply going about your day, it is important to stay aware and take preventive steps. Beat the heat. Save your heart!
The article is contributed by Prof Marcus Ong, Board Member at the Singapore Heart Foundation, Senior Consultant at the Singapore General Hospital’s Department of Emergency Medicine, and Professor at the Duke-NUS Medical School.
