Gilead Sciences has announced that nine people with hepatitis C virus (HCV) receiving treatment with Harvoni (ledipasvir/sofosbuvir) or Sovaldi (sofosbuvir) who were on the heart medication Cordarone (amiodarone) suffered from low heartbeats; one died of a heart attack, BloombergBusiness reports. Gilead has updated its label of the two hep C drugs to reflect the danger of these combinations.

Six of the individuals developed bradycardia (slower than normal heart rate) within 24 hours of starting hep C treatment; the other three did within two to 12 days. In addition the amiodarone, three were taking Harvoni, five took Sovaldi with Bristol-Myers Squibb’s daclatasvir and one took Sovaldi with Janssen’s Olysio (simeprevir).

People taking beta blockers, or who have an underlying cardiac condition or advanced liver disease, may be at increased risk for bradycardia when taking Harvoni or Sovaldi with amiodarone.

The bradycardia generally went away after the surviving individuals stopped hep C treatment.

People who develop any signs or symptoms of bradycardia should see a doctor immediately. These indicators may include near-fainting or fainting, dizziness or lightheadedness, malaise (a general feeling of unwellness), weakness, excessive fatigue, shortness of breath, chest pains, or confusion or memory problems.

To read the Bloomberg story, click here.

To read the drug label changes, click here.