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Can Heat Stroke Cause Cardiac Arrest? 

what is heat stroke

There’s a known connection between strenuous exercise and Sudden Cardiac Arrest, but where does heat factor in? 

Heat stroke is a medical emergency that claims the lives of hundreds of people in the US each year, mostly in urban areas during periods of extreme heat. Regardless of where you are in the country, you’ve likely experienced a wave of extreme heat– characterized by 2-3 days in a row where temperatures hit above 90 degrees. When temperatures rise, it’s important to take health precautions to prevent serious heat-related illnesses like heat stroke.

Put simply, hot weather makes your body work harder, particularly your body’s cardiovascular system. Added stress to the heart can increase health risks for people who have chronic conditions and heart issues, and in extreme cases, heat stroke can even lead to other medical emergencies like cardiac arrest. 

In this article, learn more about heat stroke and its relationship to heart diseases as well as what precautionary measures you can take to protect your heart when the temperatures rise. 

What is Heat Stroke?

Heat stroke is a medical emergency that is on the severe end of the heat-related illness spectrum. Like cardiac arrest, it requires immediate intervention to prevent permanent damage or death. If you suspect heat stroke, call 911 or head to the hospital, and attempt to cool the person down with whatever means are available. 

Heat stroke occurs when a person’s internal body temperature rises too quickly and their cooling systems begin to fail, meaning they are unable to sweat or use other mechanisms to cool down.  During heat stroke, the body temperature can reach up to 105-106° F within minutes, placing enormous stress on the organs as they try to curb the rising temperatures. 

What Causes Heat Stroke?

A person typically experiences heat stroke after spending intense periods of time in the sun, especially while engaged in strenuous work, play, or other activities. Dehydration, or loss of water in the body, contributes to heat stroke, too. 

Heat cramps and heat exhaustion may progress to full blown heat stroke if proper measures aren’t taken to address overheating earlier, but heat stroke can also happen in the absence of any prior symptoms.

Symptoms of Heat Stroke 

can heat stroke cause cardiac arrest

While symptoms may look different case by case, the most common symptom of heat stroke is high body temperatures–typically those that reach 103-106° F. The skin can also appear hot and flushed, dry with no sweat. A person experiencing heat stroke may have headaches, hallucinations, and signs of fatigue. 

Similar to a stroke, symptoms of heat stroke can also involve disorientation, seizures, dizziness, and loss of consciousness. 

How Can Heat Stroke Trigger a Potentially Fatal Cardiac Arrest 

In a 2021 report, the Canadian Cardiovascular Society acknowledged that heat-related deaths are most often the result of cardiovascular malfunctions, highlighting the connection between cardiac arrest and heat stroke. 

Because of a complex interplay of physiological responses to the heat, heat stroke can trigger a cardiac arrest and other dangerous arrhythmias. During a heat stroke, the body’s efforts to cool its core temperature force the heart to work harder to deliver blood throughout the body and maintain vital organ functioning. This can be especially dangerous for individuals who have pre existing heart conditions, like hypertension, coronary artery disease, or congestive heart failure, and are already at a greater risk of cardiovascular complication. 

Some medical reviews even suggest that experiencing heat stroke can lead to long term cardiovascular disease.

Who is Most at Risk? 

Just like Sudden Cardiac Arrest, anyone can experience heat stroke if the temperature and activity level is high enough. 

That being said, infants, children, and the elderly possess elevated risks for developing heat stroke since their bodies are not as well equipped to regulate core temperatures effectively. 

People who work outdoors, the economically disadvantaged (unhoused), and people who are on certain medications or drinking alcohol are more likely to experience heat stroke. As well, having obesity or certain diseases (like cystic fibrosis) that prevent the body from sweating properly can put someone at a higher risk for heat stroke

How to Protect Your Heart During High Temperatures 

Like Sudden Cardiac Arrest, the sense of urgency when dealing with heat stroke is paramount. If you suspect someone is experiencing heat stroke or cardiac arrest induced by high temperatures, call 911 right away. 

Stay Hydrated

Extreme heat can lead to dehydration, which puts additional pressure and stress on the heart. Prioritize hydration in high temperatures by consuming enough water will help the body regulate its temperature. 

Keep an AED on Hand

Have an automated external defibrillator, or AED, available at gatherings in the heat, such as concerts, sports events, or outdoor work (think construction, farming, landscaping, etc.) for swift response to cardiac emergencies. 

The Avive Connect AED is made to go wherever you do.

Acclimate to Weather 

Give your body time to adapt to hot weather conditions gradually to avoid stressing your cardiovascular system.

School and youth athletic programs usually see the most heat related issues at the onset of fall sports season since many students may not have been training over the summer and are not used to the warm temperatures.

Have an Emergency Action Plan for Heat Stroke 

Be prepared with a heat stroke emergency plan, ensuring that there are immediate measures available to help a person cool down. Whether this means bringing a tent for shade to sporting events or coolers full of ice, there are several ways to prepare to respond to heat related emergencies. 


While there’s a lot left to be explored in the connections between heat, heat stroke, and cardiac arrest, studies show us that high temperatures put stress on the heart and can increase the risk for medical emergencies like cardiac arrest. This becomes especially true when exercise is involved. 

While we can’t change the weather, we can prepare for it, and protect our hearts in the process. 

Heat Stroke FAQ

What happens to your heart when you overheat?

When your body overheats, your heart has to work harder to regulate the body temperature–it pumps more blood to the skin for cooling, which can raise the heart rate or stress the cardiovascular system. 

Can heat stroke feel like a heart attack?

Heat stroke and heart attack have some overlapping  symptoms like shortness of breath, nausea, and confusion. Seek immediate medical attention if you are experiencing these symptoms in a hot environment.  

Can heat stroke damage your heart?

Prolonged heat stroke can damage the heart muscle by causing inflammation and potentially triggering arrhythmias. To protect the heart, it is crucial to take caution in extreme heat and treat symptoms of heat stroke immediately. 

How hot is too hot for heart patients?

Extreme heat is categorized as 2-3+ days where temperatures are above 90 F. Heart patients are advised to avoid extreme heat whenever possible. Everyone should prepare for extreme heat  by making sure to wear appropriate clothing, drink enough fluids, and limit outdoor activities. 

What is the first aid of heat stroke?

Heat stroke is a medical emergency and should be treated immediately by calling 911. Someone experiencing heat stroke needs to be cooled down right away, so do whatever you can to cool the person by: moving them to a cooler place, applying ice packs to the body, immersing them in cold water, and removing any clothing that is too tight or heavy. 

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