Can Bariatric Surgery Control Blood Pressure Long-Term?

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

SYNOPSIS: A randomized trial comparing bariatric surgery to medical therapy in hypertensive obese patients has shown that bariatric surgery effectively lowers blood pressure over five years of follow-up.

SOURCE: Schiavon CA, Cavalcanti AB, Oliveira JD, et al. Randomized trial of effect of bariatric surgery on blood pressure after 5 years. J Am Coll Cardiol 2024;83:637-648.

GATEWAY (GAstric bypass to Treat obEse Patients With steAdy hYpertension) is a randomized trial comparing bariatric surgery to medical therapy of hypertension in subjects with obesity, which showed a significant reduction in the need for antihypertension medications in the bariatric group at three years. The Schiavon et al study presents the five-year follow-up data. GATEWAY is a randomized, non-blinded, single-center clinical trial performed at the Heart Hospital in Sao Paulo, Brazil. The investigators enrolled 100 patients with a body mass index (BMI) of 30 kg/m² to 39.9 kg/m² and established hypertension treated with at least two medications at maximal dosage or more than two medications at moderate doses.

Exclusion criteria included systolic blood pressure (SBP) > 180 mmHg or diastolic BP (DBP) > 120 mmHg, overt cardiovascular disease, secondary hypertension, current smokers, type 1 diabetes, or type 2 diabetes with a glycated hemoglobin of > 7.0%. Subjects were randomized to Roux-en-Y gastric bypass (RYGB) plus medical therapy or medical therapy for hypertension alone. All subjects were counseled about weight loss, exercise, reduced salt intake, and increased potassium intake. Every 12 months, ambulatory blood pressure (ABP), clinic BP, echocardiography, and laboratory values were obtained.

The primary outcome was at least a 30% reduction in the total number of antihypertension medications while maintaining BP < 140/90 mmHg. In addition, the researchers evaluated the post hoc outcomes of hypertension remission (< 130/90 mmHg off medications), American Heart Association (AHA)/American College
of Cardiology (ACC) guideline hypertension goal (< 130/80 mmHg), and resistant hypertension (BP control on more than three medications). Initially, 50 patients were assigned to each group. Four patients did not undergo RYGB, two patients died (one in each group), and 29 patients were lost to follow-up, leaving 37 (74%) in the gastric bypass group and 32 (64%) in the medical group at five-year follow-up. The primary outcome occurred in 81% of the RYGB group and 14% of the medical group (relative risk, 5.91; 95% confidence interval, 2.58-13.52; P < 0.001) on an intention-to-treat basis. In the subjects who completed the study, the primary outcome occurred in 87% of the RYGB group and in 7% of the medical group (6.92, 2.74-17.46, P < 0.001). Also, RYGB compared to medical therapy showed significant reductions in weight, BMI, and waist circumference: BMI 36 in the medical group and BMI 28 in the RYGB group (P < 0.001).

In addition, there was a reduction in the number of hypertension medications in the RYGB group to 0.8 vs. 3.0 in the medical group. Although BP generally was lower in the RYGB group, the ABP patterns did not differ significantly between the two groups. Left atrial diameter increased in the medical group. In the RYGB group, 47% exhibited hypertension remission vs. 2% in the medical group. Resistant hypertension was 0% in the RYGB group and 15% in the medical group.

The AHA/ACC guideline BP goal was achieved in 55% of the RYGB group and 9% of the medical group (P < 0.001). In the RYGB group, one patient had an anastomosis abscess requiring reoperation and two patients had stomach ulcers that were successfully treated conservatively. The authors concluded that in subjects with obesity and hypertension, bariatric surgery is an effective and durable strategy to control hypertension.

COMMENTARY

With the advent of glucagon-like peptide-1 (GLP-1) receptor agonists for weight loss (e.g., semaglutide), why are we talking about bariatric surgery? Because recidivism is high with any weight loss program, be it diet, exercise, or drugs. Also, studies have shown that after withdrawal of GLP-1 receptor agonists, patients regained two-thirds of their prior weight loss in one year. Thus, the durability of weight loss over five years by bariatric surgery as shown in the Schiavon et al study is an important positive feature.

Hypertension is the leading cause of cardiovascular disease, and the majority of hypertensive patients are overweight or obese. Obesity often is associated with other cardiovascular disease risk factors, such as diabetes, dyslipidemia, and sedentariness. Durable weight reduction favorably affects all these factors.

What about the cost of surgery? There currently are no cost effectiveness data available for surgery compared to medical therapy, but given the current cost of the GLP-1 agonists, bariatric surgery could well be competitive.

The strengths of this study are that it is the only randomized trial focusing on blood pressure and the five-year follow-up data. There are weaknesses as well. Except for the echocardiography and ambulatory blood pressure data, it was open-label. However, to blind the study would require sham surgery. The number of patients was too small to assess mortality or cardiovascular events. It was done at a single center and only RYGB was used. The sleeve gastrectomy procedure is used more commonly because it is less complex and has an earlier recovery time. Comparative studies of the two techniques have shown that they are equally effective at weight loss, but definitive comparative data on hypertension are lacking.

Medical therapy primarily focused on dietary counseling and not drug therapy. Exercise was encouraged but not measured. GLP-1 agents were not available in Brazil at the time the study was designed and the only other weight loss drug available was a sympathomimetic, which is contraindicated with hypertension. Finally, the researchers had a significant loss of follow-up, to which the pandemic contributed. In summary, bariatric surgery should remain an important part of our repertoire for treating obese hypertensive patients, especially if the simpler sleeve gastrectomy is as good as the RYGB at maintaining normotension.