Can Bariatric Surgery Control Blood Pressure Long-Term?

This is a summarized version of the full in-depth article on Relias Media.

By Michael H. Crawford, MD. Professor of Medicine, Lucy Stern Chair in Cardiology, University of California, San Francisco.

GATEWAY Trial Overview

The GATEWAY (GAstric bypass to Treat obEse Patients With steAdy hYpertension) trial was a randomized, non-blinded, single-center study conducted at the Heart Hospital in Sao Paulo, Brazil, aimed at comparing the effects of bariatric surgery (Roux-en-Y gastric bypass, or RYGB) vs.standard medical therapy on hypertension in obese patients. The five-year follow-up data, published by Schiavon et al, builds on the previously reported three-year outcomes, offering long-term insights into the effectiveness of bariatric surgery in reducing the need for antihypertension medications in patients with obesity and hypertension.

Study Design and Population

A total of 100 patients were enrolled, with a body mass index (BMI) between 30 kg/m² and 39.9 kg/m², all of whom had established hypertension requiring treatment with at least two high-dose antihypertensive medications or more than two medications at moderate doses. Exclusion criteria included uncontrolled hypertension (systolic blood pressure > 180 mmHg or diastolic blood pressure > 120 mmHg), overt cardiovascular disease, secondary hypertension, smoking, and diabetes (type 1 or poorly controlled type 2). Participants were randomly assigned to either RYGB plus medical therapy or medical therapy alone. Both groups received counseling on weight loss, diet, and exercise.

Primary and Secondary Outcomes

The primary endpoint was defined as a 30% or greater reduction in the number of antihypertension medications while maintaining blood pressure below 140/90 mmHg. Secondary outcomes included rates of hypertension remission, meeting the American Heart Association (AHA) and American College of Cardiology (ACC) hypertension goal (< 130/80 mmHg), and prevalence of resistant hypertension.

At the five-year mark, 74% of the RYGB group (37 patients) and 64% of the medical group (32 patients) completed the study. The primary outcome was achieved in 81% of the RYGB group compared to 14% in the medical therapy group, translating to a relative risk of 5.91 (95% confidence interval, 2.58-13.52; P < 0.001). In those who completed the study, the numbers were even more striking, with 87% of the RYGB group vs.7% in the medical therapy group achieving the primary endpoint. Additionally, weight reduction and reductions in BMI and waist circumference were more significant in the RYGB group, with BMI averaging 28 compared to 36 in the medical therapy group.

Blood Pressure and Medication Use

The number of antihypertension medications required was dramatically reduced in the RYGB group (0.8 medications) compared to the medical group (3.0 medications). Although systolic and diastolic blood pressures tended to be lower in the RYGB group, there was no significant difference in ambulatory blood pressure (ABP) patterns between the two groups. The RYGB group also showed a reduction in left atrial diameter, a marker associated with cardiac strain, whereas this increased in the medical therapy group.

Remission of hypertension (defined as blood pressure < 130/90 mmHg without medications) was achieved in 47% of the RYGB group compared to just 2% in the medical group. The prevalence of resistant hypertension was 0% in the RYGB group but 15% in the medical group. Additionally, the AHA/ACC goal of blood pressure control (< 130/80 mmHg) was achieved in 55% of the RYGB group vs.only 9% in the medical therapy group.

Adverse Events and Safety

The RYGB group experienced a few adverse events, including one patient requiring reoperation for an anastomotic abscess and two patients who developed stomach ulcers, both of which were treated conservatively. Despite these events, the study concluded that bariatric surgery is an effective and durable intervention for managing hypertension in obese patients.

Commentary and Implications

The Schiavon et al study provides robust evidence for the long-term benefits of bariatric surgery in reducing antihypertension medication use and improving blood pressure control in obese patients. With the increasing use of GLP-1 receptor agonists like semaglutide for weight loss, the question arises whether bariatric surgery is still relevant. The study emphasizes that while pharmacotherapy shows promise, the durability of weight loss achieved through bariatric surgery remains a significant advantage. Recidivism, or the tendency to regain weight after stopping medication, is a concern with drugs like GLP-1 agonists, where patients often regain two-thirds of the lost weight within a year of discontinuation.

Bariatric surgery offers durable weight reduction, which positively impacts other cardiovascular risk factors such as diabetes, dyslipidemia, and physical inactivity. Although cost-effectiveness studies comparing bariatric surgery and medical therapy are currently lacking, the high cost of GLP-1 agonists may make surgery a more competitive long-term option.

Study Limitations

While the GATEWAY trial offers valuable insights, it has some limitations. The study was non-blinded, except for the echocardiography and ABP data. Blinding would have required a sham surgery, which was not feasible. Additionally, the sample size was relatively small, limiting the ability to assess hard outcomes such as mortality or cardiovascular events. The trial also only evaluated RYGB, whereas sleeve gastrectomy is a more commonly used procedure today. Sleeve gastrectomy offers similar weight loss outcomes but with less complexity and quicker recovery times, although comparative data on hypertension outcomes remain insufficient.

Summary

Bariatric surgery, specifically RYGB, provides a powerful tool for managing hypertension in obese patients, with substantial long-term benefits. Given the study's findings and the limitations of current pharmacotherapy, bariatric surgery remains an important option, especially when simpler procedures like sleeve gastrectomy may offer similar benefits.

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We discuss bariatric surgery and controlling blood pressure long-term in more detail in our full write-up on Relias Media.

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