Sudden cardiac arrest happens when the heart suddenly stops pumping blood effectively.
Within seconds, a person may collapse, lose consciousness and stop breathing normally because the brain and other organs are no longer getting enough blood and oxygen.
Unlike a heart attack, which usually happens when blood flow to part of the heart is blocked, cardiac arrest is mainly an electrical problem that stops the heart from beating properly. It is a medical emergency, and immediate CPR and use of a defibrillator can greatly improve the chance of survival.
Sudden cardiac arrest is a major cause of death in Europe. It is responsible for about half of deaths related to heart disease and roughly one in five natural deaths, yet predicting who will experience it remains extremely difficult.
Some people have warning signs such as chest pain, shortness of breath, nausea or unusual discomfort before cardiac arrest. Others have no clear warning at all, which is one reason researchers continue to look for hidden factors that may raise the risk.
Researchers from the European Sudden Cardiac Arrest network investigated whether two common blood pressure medicines could be connected to cardiac arrest. Their research was published in the European Heart Journal.
The study focused on nifedipine and amlodipine. Both medicines belong to a widely used family of drugs known as calcium channel blockers, which help blood vessels relax and make it easier for blood to flow.
Doctors commonly prescribe these medicines to treat high blood pressure. Controlling high blood pressure is important because, over time, it can damage blood vessels and increase the risk of heart attack, stroke and other serious health problems.
The researchers first studied health records from the Netherlands. They compared more than 2,500 people who had experienced sudden cardiac arrest with over 10,500 people who had not.
They found a possible warning sign involving nifedipine. People taking a high daily dose of 60 milligrams appeared to have a greater risk of sudden cardiac arrest, while the same pattern was not seen among people taking amlodipine.
The team then checked whether the finding could be seen in another population. They examined Danish data involving more than 8,000 people who had suffered cardiac arrest and about 40,000 people who had not.
The Danish results showed a similar pattern. Once again, higher-dose nifedipine was linked to a greater risk of sudden cardiac arrest, giving the researchers more reason to investigate the possible connection.
The finding attracted attention because nifedipine has been used for many years and is an established treatment for high blood pressure and chest pain. Earlier research had not clearly identified this possible danger, partly because sudden cardiac arrest is relatively difficult to study and often happens without warning.
The study does not prove that nifedipine directly causes cardiac arrest. Observational research can identify a link between a medicine and an outcome, but other differences between patients may also affect the results.
More research is therefore needed to understand why the higher dose was associated with increased risk and which patients, if any, may be especially vulnerable. Scientists also need to determine whether the finding should change the way doctors prescribe the drug.
People who currently take nifedipine should not stop taking it on their own. Suddenly changing a prescribed blood pressure treatment can create other health risks, so anyone who is concerned should discuss the medicine and its dose with a doctor or pharmacist.
The research also shows why older medicines still need continued safety monitoring. A drug can be used successfully for decades while researchers continue to learn more about how its benefits and risks may differ between doses and between patients.
If you care about heart health, please read studies about the best time to take vitamins to prevent heart disease, and calcium supplements could harm your heart health.
For more health information, please see recent studies that blackcurrants can reduce blood sugar after meal and results showing how drinking milk affects risks of heart disease and cancer.
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