Hydroxychloroquine Could Cut Recurrence of Congenital Heart Block in Half

Administering hydroxychloroquine could reduce the risk of recurrent congenital heart block in subsequent pregnancies of women with anti-SSA/Ro antibodies, regardless of health status.

Results of the Prospective Open Label Preventive Approach to Congenital Heart Block with Hydroxychloroquine(PATCH) study presented by Peter Izmirly, MD, associate professor of medicine at NYU Langone, at the 2019 American College of Rheumatology 2019 annual meeting suggest hydroxychloroquine could significantly reduce the recurrence of congenital heart block below the historical rate.

To evaluate if hydroxychloroquine could reduce the recurrence rate of congenital heart block in exposed fetuses of anti-Ro positive SLE women, investigators conducted a single-arm phase 2 clinical trial of 65 mothers. The trial used the Simon two-stage design to allow for early stopping if there were an apparent lack of treatment efficacy.

Study protocol required hydroxychloroquine initiation or maintenance at 400 mg by 10 weeks of gestation for all participants. Additionally, investigators sought to determine if treatment would decrease the rate of recurrence below the historical standard, which Izmirly pointed out previously published research has suggested is 18%.

Of the 65 mothers, 10 were considered screen failures and 1 was lost to follow up before delivery. Investigators pointed out 19 were included in the first stage of the trial and 35 were included in the second.

At the completion of the first stage, 2 of the 19 fetuses had congenital heart block. In total 4 of the 54 pregnancies resulted in congenital heart block (7.4%, P=0.02). Investigators noted 9 mothers in the study were prescribed potentially confounding medications after enrolling for lupus flares and cardiac covers apart from advanced block.

For more on the implications of these results, we sat down with Izmirly after his presentation at ACR 2019.

MD Magazine: What were the implications of your study examining the effects of hydroxychloroquine on recurrence of congenital heart block?

Izmirly: I think the overall implications are that if you've had a previously affected child with heart block, that our data shows that if you take hydroxychloroquine, you reduce your recurrence rate by more than 50% from a historical rate that we used, which was 18%. Our rate in our study was 7.4%.

So, you basically cut the disease in half—probably a little more—and I think there's substantive data out there that plaquenil is safe to use in pregnancy. If you have lupus, it's an added benefit to maintaining it during pregnancy. The data for plaquenil use in Sjögren’s syndrome is all over the place, but if you're on it, I think you should be encouraged to continue it.

Then if you are asymptomatic and only figured out that you had antibodies because your previous workup for the child show that you had the antibodies. It's a potential way to reduce the risk in your subsequent pregnancies if you so choose to have a subsequent pregnancy.