The cause of a life-threatening condition that can lead to heart failure in pregnant women could be genetic, a global study has found.
Peripartum cardiomyopathy (PPCM) can lead to a woman developing heart failure in late pregnancy or shortly after delivery. It affects up to 700 women in the UK every year, but there has previously been no clear explanation for its cause.
But Royal Brompton Hospital and Penn Cardiovascular Institute in the USA have published new findings showing a sequence of key gene variants in women with the condition.
Already known risk factors include pre-existing hypertension and preeclampsia, and most common symptoms of the condition are breathlessness and palpitations. While these can usually be treated with drugs, such as ace inhibitors and beta blockers, in the most severe cases, a heart transplant can be the only long-term option.
Researches set out to determine whether the condition is linked to the genetic mutations responsible for a condition called dilated cardiomyopathy (DCM), which shares similarities with PPCM. These include heart enlargement, drop in heart function, and even sudden death.
One in five cases are caused by variants in the TTN gene.
Researchers used a sample of 172 women with PPCM from six centres across the world, 332 people with DCM in the UK and 60,000 control subjects, and compared the prevalence of variants in 43 genes.
Around 15% of PPCM patients were found to carry variants that disrupted important heart genes. This was significantly higher than the controls but similar to the patients with DCM (17%). In particular, 10% of women with PPCM had mutations of the TTN gene, compared with just 1.4% of the controls.
This evidence suggests that PPCM can have very similar genetic characteristics to DCM, with variants of the TTN gene found to be the most prevalent genetic disposition of each disease.
Experts say the results have implications for the way the condition is treated in future and could save lives. For example, it may mean that relatives of PPCM patients are offered the same genetic screening as close families, to identify any cases as soon as possible.
James Ware, consultant cardiologist at Royal Brompton & Harefield NHS Foundation Trust and lead author of the research paper, said: "Our findings explain why a significant number of PPCM cases occur. When we looked at cases without the known risk factors we found a lot of genetic abnormalities. For example, a quarter of patients without hypertension had TTN gene mutations.
"PPCM has a mortality rate of five to 10%, so being able to shed light on why it occurs in some women and not others is an important development and could ultimately save lives. Further research is needed to better understand the value of genetic information in determining the prognosis of PPCM."