ATLANTA – Hydroxychloroquine (Plaquenil) 400 mg/day starting by pregnancy week 10 reduces recurrence of congenital heart block in infants born to women with anti-Ro antibodies, according to an open-label, prospective study presented at the annual meeting of the American College of Rheumatology.
Among antibody-positive women who had a previous pregnancy complicated by congenital heart block (CHB), the regimen reduced recurrence in a subsequent pregnancy from the expected historical rate of 18% to 7.4%, a more than 50% drop. “Given the potential benefit of hydroxychloroquine” (HCQ) and its relative safety during pregnancy, “testing all pregnancies for anti-Ro antibodies, regardless of maternal health, should be considered,” concluded investigators led by rheumatologist, MD, associate professor of medicine at New York (N.Y.) University.
About 40% of women with systemic lupus erythematosus and nearly 100% of women with Sjögren’s syndrome, as well as about 1% of women in the general population, have anti-Ro antibodies. They can be present in completely asymptomatic women, which is why the authors called for general screening. Indeed, half of the women in the trial had no or only mild, undifferentiated rheumatic symptoms. Often, “women who carry anti-Ro antibodies have no idea they have them” until they have a child with CHB and are tested, Dr. Izmirly said.
The antibodies cross the placenta and interfere with the normal development of the AV node; about 18% of infants die and most of the rest require lifelong pacing. The risk of CHB in antibody-positive women is about 2%, but once a child is born with the condition, the risk climbs to about 18% in subsequent pregnancies.
Years ago, Dr. Izmirly and his colleagues had a hunch that HCQ might help because it disrupts the toll-like receptor signaling involved in the disease process. Ahe led added weight to the idea, finding that among 257 anti-Ro positive pregnancies, the rate of CHB was 7.5% among the 40 women who happened to take HCQ, versus 21.2% among the 217 who did not. “We wanted to see if we could replicate that prospectively,” he said.
The Preventive Approach to Congenital Heart Block with Hydroxychloroquine () trial enrolled 54 antibody positive women with a previous CHB pregnancy. They were started on 400 mg/day HCQ by gestation week 10.
There were four cases of second- or third-degree CHB among the women (7.4%, P = 0.02), all detected by fetal echocardiogram around week 20.
Nine of the women were treated with IVIG and/or dexamethasone for lupus flares or fetal heart issues other than advanced block, which confounded the results. To analyze the effect in a purely HCQ cohort, the team recruited an additional nine women not treated with any other medication during pregnancy, one of whose fetus developed third-degree heart block.
In total, 5 of 63 pregnancies (7.9%) resulted in advanced block. Among the 54 women exposed only to HCQ, the rate of second- or third-degree block was again 7.4% (4 of 54, P = .02). HCQ compliance, assessed by maternal blood levels above 200 ng/mL at least once, was 98%, and cord blood confirmed fetal exposure to HCQ.
Once detected, CHB was treated with dexamethasone or IVIG. One case progressed to cardiomyopathy, and the pregnancy was terminated. Another child required pacing after birth. Other children reverted to normal sinus rhythm but had intermittent second-degree block at age 2.
Overall, “the safety in this study was excellent,” said rheumatologist and senior investigator, MD, director of the division of rheumatology at New York University.
The complications – nine births before 37 weeks, one infant small for gestational age – were not unexpected in a rheumatic population. “We were very nervous about Plaquenil cardiomyopathy” in the pregnancy that was terminated, but there was no evidence of it on histology.
The children will have ocular optical coherence tomography at age 5 to check for retinal toxicity; the 12 who have been tested so far show no obvious signs. Dr. Izmirly said he doesn’t expect to see any problems. “We are just being super cautious.”
The audience had questions about why the trial didn’t have a placebo arm. He explained that CHB is a rare event – one in 15,000 pregnancies – and it took 8 years just to adequately power the single-arm study; recruiting more than 100 additional women for a placebo-controlled trial wasn’t practical.
Also, “there was no way” women were going to be randomized to placebo when HCQ seemed so promising; 35% of the enrollees had already lost a child to CHB. “Everyone wanted the drug,” Dr. Izmirly said.
The majority of women were white, and about half met criteria for lupus and/or Sjögren’s. Anti-Ro levels remained above 1,000 EU throughout pregnancy. Women were excluded if they were taking high-dose prednisone or any dose of fluorinated corticosteroids at baseline.
The National Institutes of Health funded the work. The investigators had no relevant disclosures.
SOURCE: Izmirly P et al. Arthritis Rheumatol. 2019;71(suppl 10). Abstract