Swiss hospitals report rising cardiovascular emergencies during heatwave

Swiss hospitals are seeing more cardiovascular emergencies during periods of extreme heat, with Zurich reporting a particularly sharp increase, Swiss broadcaster SRF reported.

The cardiology department at Zurich University Hospital has recorded a clear rise in cardiovascular emergencies over the past few weeks. The department is currently “full to the brim,” chief physician Frank Ruschitzka told the Tages-Anzeiger, citing the prolonged heat as the main cause.

In 2025, the hospital had already recorded a 30 percent increase in cases compared with the corresponding months of previous years. Hospital officials told the Tages-Anzeiger that this year’s figures are likely to be similar.

Mixed picture at other hospitals

Lucerne Cantonal Hospital also reported a noticeable increase in emergency admissions that led to inpatient treatment compared with last summer.

Basel University Hospital has not seen a 30 percent increase, according to Felix Mahfoud, its chief physician for cardiology. St Gallen Cantonal Hospital said it had not experienced more pronounced events or greater pressure during this year’s heatwaves than on other hot days.

Bern’s Inselspital reported more visits for dehydration among patients with heart failure. The number of cardiac catheter examinations, however, had not increased.

Why heat puts pressure on the heart

Heat causes the body’s blood vessels to expand and leads to fluid loss, forcing the heart to work harder. High humidity can worsen the problem because the body is less able to release excess heat through sweating.

The risk of cardiovascular emergencies increases when outdoor temperatures remain high for extended periods and do not fall significantly overnight. Because several factors can contribute to an individual case, the direct link between heat and cardiovascular emergencies is difficult to prove.

Symptoms and risk groups

Symptoms are often non-specific and can include dizziness, weakness, tiredness, headaches and a rapid heartbeat. People with heart disease may also experience shortness of breath, chest pain, fluid retention or cardiac arrhythmias.

Loss of consciousness, confusion and fainting are clear warning signs that should not be ignored. Heat can also worsen existing cardiovascular disease and destabilise heart failure.

People aged over 75 are particularly at risk, as are those with heart failure, coronary heart disease, high blood pressure, cardiac arrhythmias, kidney failure, cancer or diabetes. People taking diuretic medication also face an increased risk.

Mahfoud said particular attention should be paid to people who live alone, people with dementia or mental illnesses, and patients with several simultaneous illnesses.

How to protect against the heat

The most important measure is to drink enough, even without feeling thirsty. Physical exertion should be scheduled for the cooler morning or evening hours. People should avoid direct sunlight and ensure air movement.

Anyone experiencing warning signs such as dizziness, tiredness, confusion or circulatory problems should respond early and seek medical advice.