Study: cooling temperatures increase risk of cardiac arrests

Colder Days Linked to Higher Risk of Cardiac Arrests Outside Hospital

Poinews.com – Study – Lower temperatures may place added strain on people at risk of serious heart problems, with new research finding a measurable rise in out-of-hospital cardiac arrests as the weather cools.

The nationwide study, published in the journal Public Health, examined more than 114,000 cases in Hungary and found that each 1°C fall in average daily temperature was associated with a 1.4% increase in the daily number of cardiac arrests occurring outside medical settings.

Researchers from Semmelweis University in Budapest, the Budapest University of Technology and Economics, and the Hungarian National Ambulance Service reviewed cases recorded between November 2018 and December 2023. They matched the incidents with daily weather conditions, including temperature, wind speed, air pressure, humidity and air quality.

Winter brought substantially more cases

The seasonal difference was also clear. Nearly 18% more out-of-hospital cardiac arrests occurred during winter than during summer, highlighting that the concern is not limited to isolated cold-weather events.

Sudden drops in temperature can matter, but the findings suggest that persistently cooler conditions may also increase danger. A fall of more than 5°C within a day could be useful as an alert threshold for an early-warning system, the researchers said.

That does not mean cold weather directly causes every cardiac arrest. Cardiac arrests have many possible triggers and underlying health factors. However, the analysis points to temperature as one of the most significant weather-related indicators linked with a higher number of emergencies.

Cold conditions can be especially demanding for the cardiovascular system. For people with existing heart or circulatory disease, periods of falling temperatures may be a time to pay closer attention to symptoms, follow prescribed treatment plans and ensure relatives know what to do if an emergency occurs.

The impact can arrive days later

A notable feature of the research is that the effect of changing weather was not always immediate. Increased numbers of cardiac arrests could emerge up to three days after the meteorological shift.

This delayed pattern could make weather forecasts more useful for emergency planning. Forecast-based models may be able to identify periods when out-of-hospital cardiac arrest numbers are likely to exceed normal levels as much as three days ahead.

Such forecasts could help ambulance services and hospitals prepare for a heavier workload. They could also give patients with cardiovascular conditions and their families advance notice that a higher-risk period may be approaching.

For the public, the finding reinforces the importance of fast action when a person collapses and becomes unresponsive. Out-of-hospital cardiac arrest is a medical emergency in which immediate contact with emergency services and prompt resuscitation efforts can be crucial while professional help is on the way.

A major emergency-health challenge in Europe

Out-of-hospital cardiac arrest, often shortened to OHCA, remains one of the leading causes of death in developed countries. Across Europe, annual rates range from 67 to 170 cases for every 100,000 residents. Survival remains below 10%.

Those figures underline why better anticipation matters. If emergency systems can identify circumstances linked with a coming rise in cases, they may be better positioned to organise staff and resources. Public warnings can also remind people of the value of rapid assistance and cardiopulmonary resuscitation, commonly known as CPR.

The Hungarian analysis adds weather patterns to the list of factors that may help health services anticipate demand. Temperature, wind, pressure, moisture levels and air quality were all included in the review, allowing the team to assess how cardiac arrest numbers changed alongside daily meteorological conditions.

Among those signals, declining temperature stood out. The research suggests that a cold snap is not the only moment deserving attention: lower average temperatures across a period can also be associated with more emergencies.

Preparing for colder spells

For individuals living with cardiovascular disease, the study offers a practical reminder to take colder weather seriously. Maintaining regular medical care, keeping essential medicines available and discussing emergency plans with close family members can help people feel more prepared when conditions become harsher.

Families and communities also have a role. Recognising an unresponsive person, calling emergency services immediately and starting CPR when appropriate are key parts of the response to cardiac arrest. Wider awareness of these steps remains important because the condition often occurs away from hospitals, where every minute can affect the chances of survival.

The researchers’ forecast approach is still a tool for anticipating pressure on emergency care rather than a guarantee that any one person will have a cardiac event. Yet the ability to spot higher-risk days in advance could give medical services and vulnerable households a valuable opportunity to prepare.

As temperatures fall, the study’s central message is straightforward: changing weather can have consequences that extend beyond comfort and convenience. In colder periods, the effects on heart-health emergencies may be felt not only on the day temperatures decline, but for several days afterwards.