Just about half the country has legalized recreational cannabis, with at least some more states likely to consider it in the near future. But as enjoyable as cannabis can be for many, research out today may highlight a possible drawback of the drug: a higher risk of cardiovascular problems.

Researchers in Boston looked at hospitalization rates in parts of the country that legalized cannabis earlier than others. Compared to the pre-legalization era and to non-adopters, rates of several cardiovascular outcomes—including heart attacks—rose in the western half of the U.S. that first adopted recreational cannabis, they found.…