Study Links Serious Bleeding Risks to Diltiazem Combination Therapy With Anticoagulants for Atrial Fibrillation

Individuals taking high-blood pressure medications like Cardizem and generic diltiazem in combination with certain anticoagulant blood thinners, such as Eliquis and Xarelto, face a greater risk of serious bleeding and risk of death, according to the findings of a new study.

Researchers from Vanderbilt University in Tennessee report that the risk of bleeding from taking Cardizem (diltiazem) in combination with Xarelto or Eliquis is much greater than those faced by patients taking Lopressor, another hypertension drug. The findings were published on April 15 in the Journal of the American Medical Association (JAMA).

Cardizem belongs to a class of medications known as calcium channel blockers, which are used to treat high blood pressure and slow the rhythm of the heart in patients who have atrial fibrillation; a life-threatening condition that causes rapid or irregular heart rhythms.

In contrast, drugs like Lopressor (metoprolol) treat high blood pressure and chronic chest pain. Research indicates medications like Cardizem can help treat atrial fibrillation, but interact with other drugs, especially anticoagulant drugs like Eliquis and Xarelto. Drugs like Lopressor don’t.

However, using Cardizem with Xarelto or Eliquis is the standard of care most doctors prescribe to patients to treat atrial fibrillation, which could put many patients at risk.

In this latest study, researchers examined data on more than 204,000 Medicare patients older than 65 years with atrial fibrillation who had recently filled prescriptions for Eliquis or Xarelto, from 2012 to 2020.

They compared patients who were also taking medications to treat atrial fibrillation (AFib), either diltiazem, known by the brand names Cardizem and Viazem, or Lopressor.

Patients taking the combination of Cardizem with Eliquis or Xarelto faced an increased risk of bleeding-related hospitalization and a higher risk of death compared to patients taking the combination of Lopressor with Eliquis or Xarelto; two drugs already linked with an increased risk of death, and a higher risk of suffering from strokes and brain bleeds.

The risks were particularly high for patients given doses of Cardizem that exceeded 120 milligrams per day, the researchers determined.

The findings could have significant impact, since researchers estimate more than 6 million people in the United States have atrial fibrillation. The condition puts them at an increased risk of suffering from stroke, heart failure, dementia, and death.

Treating atrial fibrillation is estimated to cost the U.S. healthcare system more than $25 billion every year.