Gastric bypass associated with a lower incidence of MACE vs. sleeve gastrectomy over an 11-year follow-up

Gastric bypass (GB) is associated with a lower incidence of major adverse cardiac events (MACE) compared to sleeve gastrectomy (SG) over an 11-year follow-up, according to researchers from Switzerland. However, while both procedures are effective for weight loss and improving cardiovascular outcomes, gastric bypass may be associated with greater cardiovascular benefits.

The researchers stated that both there surgical procedures have well-documented benefits for obesity-related comorbidities, comparative long-term data on cardiovascular outcomes remain limited and often lack sufficient power in clinical trials. Subsequently, they sought to assess whether there is a difference in MACE after GB vs SG. Building on a previous seven-year analysis1, this latest study extended the follow-up period to 11 years and incorporated additional end points, including all-cause mortality.

Using data from the Federal Statistical Office in Switzerland (Bundesamt für Statistik), this database includes all Swiss inpatient discharge records from acute care, general, and specialty hospitals in Switzerland. Individual-level data on patient demographics, health care utilisation, hospital typology, medical diagnoses, diagnostic tests, clinical procedures, in-hospital patient outcomes, and date of death were provided for all hospitalized patients in Switzerland.

The primary composite outcome of four-point MACE consisted of acute MI, ischemic stroke, HF and all-cause mortality. Secondary outcomes of interest included the individual components of MACE, any revision surgery (any abdominal surgery potentially related to the index bariatric procedure but not directly affecting bariatric physiology), conversion surgery (any surgery modifying the index bariatric procedure), gastroesophageal reflux disease (GERD), hospitalisation for dumping syndrome and psychiatric disorders needing hospitalisation. Secondary short-term outcomes were all-cause in-hospital mortality and 30-day hospital readmissions.

Between July 2012 and December 2022, 39,867 eligible patients were identified. After weighting, 39 067 patients were included in the main analysis, with 30,270 patients (77.5%) undergoing GB and 8,797 patients (22.5%) undergoing SG.

Outcomes

After a median follow-up period of 5.1 years, 593 events (1.9%) were identified in the GB group and 276 events (3.0%) in the SG group, with event rates of 3.64 and 6.35 per 1000 patient-years, respectively. After adjustment, the risk of MACE was lower in the GB group vs. the SG group, with an adjusted HR of 0.83 (95% CI, 0.71-0.97). Among the individual components of MACE, acute MI was observed less frequently in gastric bypass patients, with no differences otherwise between groups.

After weighting, a total of 577 patients (1.9%) in the GB group and 264 (3.0%) in the SG group experienced MACE (incidence rates of 3.96 and 5.10 per 1000 patient-years, respectively). The weighted HR for MACE in the GB group vs the SG group was 0.75 (95% CI, 0.64-0.88). These findings were driven by a lower event rate of acute MI (HR, 0.60; 95% CI, 0.43-0.82) in the GB group, while the risks of ischemic stroke, HF and all-cause mortality were comparable between the groups. The cumulative incidence depicted in the  inverse probability of treatment weighting (IPW) Kaplan-Meier plots for MACE and its individual components was consistent with these findings (Figures 1 and 2).

Figure 1: Inverse probability–weighted (IPW) Kaplan-Meier curves for MACE, with the follow-up truncated at 9 years postsurgery. Number at risk represents the number in the pseudo-population generated by the IPW. HR indicates hazard ratio.

Figure 2

After weighting, consistent with the adjusted analysis, patients undergoing GB had a lower risk of conversion surgery and for GERD or peptic ulcer disease. However, patients in the GB group had an almost four-fold increased risk of reoperation for revision of the initial surgery and were more likely to be hospitalised for dumping syndrome and for psychiatric disorders. After adjustment, there were no differences in in-hospital mortality, all-cause 30-day readmission or immediate in-hospital complications.

However, following IPW, the risk of in-hospital mortality and all-cause 30-day readmission remained similar between the procedures, but GB was associated with a higher risk for immediate in-hospital complications.

After 1:1 propensity score (PS) matching between the two groups, there were 9,008 matched pairs each. While there was evidence suggesting a lower likelihood of four-point MACE in patients undergoing gastric bypass, the difference between the groups did not reach statistical significance.

Another sensitivity analysis was conducted excluding 1,144 patients who underwent conversion surgery, leaving 30,301 patients undergoing GB and 8,422 patients undergoing SG. Baseline characteristics remained balanced after IPW, and the GB group consistently exhibited a lower rate of MACE vs. the SG group, consistent with the primary analysis.

This nationwide cohort study, which spans 11 years and encompasses over 39 000 patients in Switzerland, showed 2 key findings. First, GB was associated with a lower risk for MACE compared to SG, primarily due to lower rates of MI. Second, the safety outcomes—such as common complications, reoperations, and bariatric conversions—were consistent with existing literature. GB was linked to higher rates of short-term complications and revisions, while patients undergoing SG had a higher incidence of GERD and a greater likelihood of requiring conversion surgery due to suboptimal clinical response, GERD, or both.

The study authors concludes that these findings must be balanced against the higher risk of postoperative complications and the need for surgical revisions after gastric bypass, emphasising the importance of individualised patient selection and shared decision-making in clinical practice.

The findings were reported in the paper, ‘Major Adverse Cardiac Events After Gastric Bypass vs Sleeve Gastrectomy’, published in JAMA Surgery.

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Reference

1.      Wildisen  A, Peterli  R, Werder  G,  et al.  Rate of cardiovascular events and safety outcomes seven years following gastric bypass versus sleeve gastrectomy.  Ann Surg Open. 2023;4(2):e286.