Medeiros e Melo et al report a case of a patient with pre-eclampsia and peripartum
cardiomyopathy (PPCM) successfully treated with the dopamine receptor D2 agonist cabergoline.[1] Treatment with the dopamine receptor agonist bromocriptine is currently being evaluated
in a multicenter clinical trial[2] (NCT00998556) that is based on the concept of dopamine agonists inhibiting the enzymatic
generation of prolactin-fragments (etiologically linked to PPCM) by substrate depletion,
that is, the inhibition of pituitary prolactin secretion. These prolactin-fragments
are termed vasoinhibins, and represent a family of hormones with effects on the angiogenesis-mediated
growth of reproductive and non-reproductive organs, and in the pathogenesis of a variety
of diseases, such as pre-eclampsia, PPCM, and diabetic retinopathy.[3]
[4]
[5]
[6]
[7] In PPCM, vasoinhibins cause heart failure by impairing coronary microvascular growth
and function.[3]
While the report by Medeiros e Melo et al is consistent with the above-mentioned concept,
it lacks important information for claiming a similar mechanism. The authors refer
to vasoinhibins as “products of prolactin degradation”, thereby contradicting their
role as key pathological mediators. Furthermore, the work does not contain any information
on the serum levels of prolactin nor of vasoinhibins. While vasoinhibin serum levels
are difficult to evaluate due to the lack of a quantitative vasoinhibin-assay, prolactin
levels should have been measured throughout the course of the treatment. It is puzzling
that starting the treatment with cabergoline on the 39th day post-abdominal delivery
was effective, since, in the absence of lactation, prolactin levels return to the
non-pregnant level within the first few weeks. Did the authors check for prolactinoma
evidence? Additionally, monitoring of cardiac markers as natriuretic peptides and
troponin serum levels would be of interest. In view of the scarce data about prolactin
serum levels before, during, and after PPCM with or without dopamine receptor agonists,
we recommend strict monitoring of prolactin serum levels throughout the course of
the disease.
