Bariatric Surgery Leads to Better Cardiovascular Function in Pregnancy

Becky McCall

June 23, 2021

Pregnant women with a history of bariatric surgery have better cardiovascular adaptation to pregnancy compared with women who have similar early-pregnancy body mass index (BMI) but no history of weight loss surgery, new data suggest.

"Pregnant women who have had bariatric surgery demonstrate better cardiovascular adaptation through lower blood pressure, heart rate, and cardiac output, more favorable diastolic indices, and better systolic function," reported Deesha Patel, MBBS MRCOG, specialist registrar, Chelsea and Westminster Hospital, London, United Kingdom.

"Because the groups were matched for early pregnancy BMI, it's unlikely that the results are due to weight loss alone but indicate that the metabolic alterations as a result of the surgery, via the enterocardiac axis, play an important role," Patel continued.

The findings were presented at the Royal College of Obstetricians and Gynecologists 2021 Virtual World Congress.

Although obesity is known for its inflammatory and toxic effects on the cardiovascular system, it is not clear to what extent the various treatment options for obesity modify these risks in the long term, said Hutan Ashrafian, MD, clinical lecturer in surgery, Imperial College London, London, United Kingdom.

"It is even less clear how anti-obesity interventions affect the cardiovascular system in pregnancy," Ashrafian told Medscape Medical News.

"This very novel study in pregnant mothers having undergone the most successful and consistent intervention for severe obesity ― bariatric or metabolic surgery ― gives new clues as to the extent that bariatric procedures can alter cardiovascular risk in pregnant mothers," continued Ashrafian, who was not involved in the study.

The results show how bariatric surgery has favorable effects on cardiac adaptation in pregnancy and in turn "might offer protection from pregnancy-related cardiovascular pathology such as preeclampsia," explained Ashrafian. "This adds to the known effects of cardiovascular protection of bariatric surgery through the enterocardiac axis, which may explain a wider range of effects that can be translated within pregnancy and possibly following pregnancy in the postpartum era and beyond."

A History of Bariatric Surgery vs No Surgery

The prospective, longitudinal study compared 41 women who had a history of bariatric surgery with 41 women who had not undergone surgery. Patients' characteristics were closely matched for age, BMI (34.5 kg/m2 and 34.3 kg/m2 in the surgery and bariatric surgery groups, respectively) and race. Hypertensive disorders in the post-surgery group were significantly less common compared with the no-surgery group (0% vs 9.8%).

During the study, participants underwent cardiovascular assessment at 12–14 weeks, 20–24 weeks, and 30–32 weeks gestation. The assessment included measurement of blood pressure and heart rate, transthoracic echocardiography, and 2D speckle tracking, performed offline to assess global longitudinal and circumferential strain.

Blood pressure readings across the three trimesters were consistently lower in the women who had undergone bariatric surgery compared with those in the no-surgery group, and all differences were statistically significant. Likewise, heart rate and cardiac output across the three trimesters were lower in the post-surgery cohort. However, there was no difference in stroke volume between the two groups.

As for diastolic function, there were more favorable indices in the post-surgery group with a higher E/A ratio, a marker of left ventricle filling (P < .001), and lower left atrial volume (P < .05), Patel reported.

With respect to systolic function, there was no difference in ejection fraction, but there was lower global longitudinal strain (P < .01) and global circumferential strain in the post-bariatric group (P = .02), suggesting better systolic function.

"Strain is a measure of differences in motion and velocity between regions of the myocardium through the cardiac cycle and can detect subclinical changes when ejection fraction is normal," she added.

"This is a fascinating piece of work. The author should be congratulated on gathering so many [pregnant] women who had had bariatric surgery. The work gives a unique glimpse into metabolic syndrome," said Philip Toozs-Hobson, MD, who moderated the session.

"We are increasingly recognizing the impact [of bariatric surgery] on metabolic syndrome, and the fact that this study demonstrates that there is more to it than just weight is important," continued Toosz-Hobson, who is a consultant gynecologist at Birmingham Women's Hospital NHS Foundation Trust, Birmingham, United Kingdom.

Cardiovascular Benefits of Bariatric Surgery

Bariatric surgery has been associated with loss of excess body weight of up to 55% and with approximately 40% reduction in all-cause mortality in the general population. The procedure also reduces the risk for heart disease, diabetes, and cancer.

The cardiovascular benefits of bariatric surgery include reduced hypertension, remodeling of the heart with a reduction in left ventricular mass, and an improvement in diastolic and systolic function.

"Traditionally, the cardiac changes were thought to be due to weight loss and blood pressure reduction, but it is now conceivable that the metabolic components contribute to the reverse modeling via changes to the enterocardiac axis involving changes to gut hormones," said Patel. These hormones include secretin, glucagon, and vasoactive intestinal peptide, which are known to have inotropic effects, as well as adiponectin and leptin, which are known to have cardiac effects, she added.

"Pregnancy following bariatric surgery is associated with a reduced risk of hypertensive disorders, as well as a reduced risk of gestational diabetes, large-for-gestational-age neonates, and a small increased risk of small-for-gestational-age neonates," said Patel.

Patel and Toosz-Hobson have disclosed no relevant financial relationships.

Royal College of Obstetricians and Gynecologists 2021 Virtual World Congress. Presented June 10, 2021.

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