A common drug used to treat high blood pressure may increase the risk of sudden cardiac arrest when taken at high doses, according to a new study published in the European Heart Journal.
The finding surprised many doctors because the medication has been widely used for decades and is generally considered safe. The research suggests that doctors and patients may need to use extra caution when using the drug, especially at higher doses.
Sudden cardiac arrest is one of the most dangerous heart emergencies. It happens when the heart suddenly stops beating properly. When this occurs, blood stops flowing to the brain and other vital organs. A person quickly loses consciousness and stops breathing normally. Without fast treatment, death can occur within minutes.
Sudden cardiac arrest is different from a heart attack. A heart attack happens when blood flow to part of the heart muscle becomes blocked. In contrast, sudden cardiac arrest is usually caused by a serious problem with the heart’s electrical system, which controls the heartbeat. This electrical failure causes the heart to beat in a chaotic way or stop beating entirely.
This condition is responsible for a large number of deaths around the world. In Europe, it causes about half of all deaths related to heart disease. Overall, it accounts for about one in five natural deaths. Because it happens so suddenly and often without warning, it has been difficult for scientists to study the causes and risk factors.
The new study was carried out by researchers from the European Sudden Cardiac Arrest Network. The team wanted to understand whether certain medicines might increase the risk of sudden cardiac arrest.
They focused on two drugs that belong to the same family of medications called calcium channel blockers. These drugs help relax blood vessels, lower blood pressure, and reduce chest pain caused by heart disease.
The two drugs studied were nifedipine and amlodipine. Both medications are widely prescribed around the world to treat high blood pressure and angina, a type of chest pain caused by reduced blood flow to the heart. Doctors have used these medications for many years to help prevent heart attacks and strokes by lowering blood pressure.
To investigate the possible risk, the researchers examined medical data from thousands of people in the Netherlands. They studied 2,503 patients who had experienced sudden cardiac arrest and compared them with 10,543 healthy individuals who had not had the condition.
The team then looked at whether these people were using nifedipine or amlodipine and what doses they were taking.
The results showed a concerning pattern. People who were taking a high dose of nifedipine, specifically 60 milligrams per day, had a higher risk of sudden cardiac arrest compared with people who were not taking the drug. However, the same risk was not seen in people who were taking amlodipine.
To confirm their findings, the researchers repeated the analysis using data from Denmark. This second dataset included more than 8,000 patients who had experienced sudden cardiac arrest and about 40,000 healthy individuals. The results were similar, strengthening the evidence that high doses of nifedipine may be linked to a greater risk of sudden cardiac arrest.
Scientists say the discovery is surprising because both nifedipine and amlodipine have been used safely for many years. Earlier studies had not clearly shown this risk. One reason may be that sudden cardiac arrest happens very quickly and often outside hospitals, which makes it difficult to collect detailed data.
The researchers emphasized that patients should not panic or stop taking their medications without speaking to a doctor. High blood pressure is a serious condition that can lead to heart attacks, strokes, and kidney disease if it is not treated properly. Medicines like nifedipine can still be helpful for many people.
However, the study suggests that doctors should be careful when prescribing high doses of nifedipine, especially for patients who may already have heart problems. In some cases, doctors may choose lower doses or switch to another medication such as amlodipine.
Patients should also pay attention to warning signs and talk to their doctor if they experience symptoms such as chest pain, shortness of breath, dizziness, or nausea. These symptoms can sometimes signal heart problems that require medical attention.
Preventing sudden cardiac arrest also involves healthy lifestyle choices. Eating a balanced diet, exercising regularly, avoiding smoking, and limiting alcohol can help protect heart health. Regular medical checkups are also important because they allow doctors to detect heart problems early.
For people who are at very high risk, doctors may recommend a small device called an implantable cardioverter defibrillator, or ICD. This device monitors the heart’s rhythm and can deliver a life‑saving electrical shock if a dangerous rhythm occurs.
Learning cardiopulmonary resuscitation, or CPR, can also save lives. CPR helps keep blood flowing to the brain and heart during a cardiac emergency until medical professionals arrive.
The researchers say more studies are needed to better understand why high doses of nifedipine may increase the risk of sudden cardiac arrest. Continued research will help doctors find the safest treatments for people with high blood pressure and heart disease.
The study reminds us that even well‑known medications should always be used carefully. Doctors and patients must work together to balance the benefits of treatment with possible risks. Careful monitoring, ongoing research, and open communication can help ensure that patients receive safe and effective care.
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