- FRIDAY, May 30 (HealthDay News) — Tests on mice suggest that the
drug BH4 may hold promise as a treatment for people with enlarged hearts,
says a Johns Hopkins University study.

Currently, BH4 is used to treat a genetic disorder called
phenylketonuria (PKU), a metabolic disorder in which a toxic buildup of a
molecule called phenylalanine can cause brain damage.

In this study, the Hopkins team found that BH4 stabilized the pumping
function of failing, enlarged hearts in mice and significantly decreased
the size of the heart muscle in just over a month.

“Our results show for the first time the pivotal role played by BH4 in
stopping and reversing the weakening and damage done — even in severe
cases — to the heart muscle as a result of hypertension and subsequent
hypertrophy [enlargement],” senior investigator Dr. David Kass, a
professor at the Johns Hopkins University School of Medicine and its Heart
Institute, said in a prepared statement.

“This key evidence may help us develop new therapies that stop and
reverse hypertrophy, preventing the disease from leading to end-stage
heart failure and keeping affected individuals from needing heart-assist
pumps or a treatment of last resort, the heart transplant,” Kass said.

In this study, the researchers gave a daily dose of 5 milligrams of BH4
per 25 grams of body weight to 31 mice whose hearts were damaged by
hypertension. This group of mice was compared to a group of mice with
hypertension-damaged hearts who received a placebo.

After five weeks, the BH4 group showed “remarkable improvements”
compared to the placebo group. Ejection-fraction measures of heart pumping
function improved from 48 percent at the start of BH4 treatment to 59
percent by the end of the study. In the placebo group, average pumping
function decreased from 48 percent to 35 percent.

Heart weight, as measured by muscle mass, decreased from an average of
290 milligrams at the start of BH4 treatment to an average of 209
milligrams by the end of the study. In the placebo group, average heart
weight was 330 milligrams by the end of the study.

The BH4 group also showed improvements in other areas, including heart
wall thickness, muscle cell size and fibrosis, and lowered production of
dangerous free radicals.

The study was published in the May 20 issue of Circulation.

More information

The American Heart Association has more about heart failure.