Gastric bypass a potential BP control strategy in obese patients
Gastric bypass may be an effective method of reducing blood pressure (BP) levels in obese patients with hypertension, according to findings of the GATEWAY* trial presented at the AHA** 2017 Scientific Sessions.
Nonadherence to medications presents a major problem in the management of hypertension, particularly in patients receiving multiple antihypertensive drugs, said lead author Dr Carlos Schiavon from the Heart Hospital in São Paulo, Brazil, who presented the results.
“These results have implications in minimizing nonadherence to therapy and its related consequences,” he said.
In this single-centre trial, 100 patients with BMI 30–39.9 kg/m2 and on ≥2 maximum dose or >2 moderate dose hypertension medications (mean age 43.8 years, 70 percent female, mean BMI 36.9 kg/m2) were randomized 1:1 to undergo Roux-en-Y gastric bypass in addition to medication or medication alone (control group).
Patients whose BP was at target (<140/90 mm Hg) were maintained on current medication, while for those above target, the primary medications were ACE inhibitors or ARBs plus calcium channel blockers, with thiazide diuretics, spironolactone, or clonidine prescribed as needed.
Compared with those on medication only, more patients who underwent gastric bypass met the primary endpoint of a ≥30 percent reduction in total number of antihypertensive medications while maintaining BP at <140/90 mm Hg at 12 months (83.7 percent vs 12.8 percent; rate ratio [RR], 6.6, 95 percent confidence interval [CI], 3.1–14.0; p<0.001). [AHA 2017, session LBS.03; Circulation 2017;doi:10.1161/CIRCULATIONAHA.117.032130]
At 12 months, 51 percent of patients who underwent gastric bypass demonstrated remission of hypertension (office BP <140/90 mm Hg without medication), while no patients in the control group were free of medication at the end of follow-up.
When using the SPRINT*** target as a guide (systolic BP <120 mm Hg), 22.4 percent of patients who underwent gastric bypass achieved hypertension remission compared with zero in the control group at 12 months (RR, 3.8, 95 percent CI, 1.4–10.6; p=0.005).
Twelve months post-treatment, patients who underwent gastric bypass also demonstrated better improvement than those on medication only in terms of BMI (26.8 vs 36.3 kg/m2) and waist circumference (86.9 vs 109.8 cm), as well as fasting plasma glucose (84.0 vs 98.4 mg/dL), LDL-C (86.9 vs 116.5 mg/dL), and triglyceride levels (85.7 vs 130.0 mg/dL; all p<0.001).
“Taken together with the improved metabolic and inflammatory profile, such effects have, in theory, the potential to reduce major cardiovascular events,” said Schiavon.
More patients in the gastric bypass group required rehospitalization compared with the control group (12 percent vs 0 percent; p=0.03), while incidence of hypertensive crisis requiring emergency department visit and anaemia was comparable between groups.
According to discussant Professor Paul Poirier from the Quebec Heart and Lung Institute, Quebec, Canada, there are several potential mechanisms behind these findings including insulin resistance which could influence renal sodium reabsorption, inflammation which could modulate arterial stiffness, and gut hormones such as glucagon-like peptide 1 and peptide YY which could influence electrolyte transport in the renal tubular cells as well as cause diuresis.
The researchers hope that the 4-year follow-up will help determine the long-term outcomes of bariatric surgery in this population.