For the first time, doctors have tied infection with the Zika virus to possible new heart problems in adults.

The evidence is only in eight people in Venezuela and does not prove a link. It’s too soon to know how often this might be happening.

The biggest trouble the mosquito-borne virus has been causing is for pregnant women and their fetuses. Zika has caused an epidemic of birth defects in the Caribbean and South America. Many infections cause no or only mild symptoms.

However, researchers in Venezuela say eight people with confirmed Zika infections developed a heart rhythm problem and six developed heart failure about 10 days after Zika symptoms began.

The cases will be discussed Saturday at an American College of Cardiology conference.