This was a prospective longitudinal trial; the mean age of study population was 37.2 ± 10.49 years. The majority (84%) of patients were females. These demographic characteristics were consistent with previous studies. In a meta-analysis involving 134 studies and an aggregate of 22,094 patients, 73% of them were females, with an average age of 39 years [14]. As in the current study, the population undergoing bariatric surgery is predominantly female in the fourth decade of life, probably when the metabolic and hemodynamic complications resulting from excess body weight appear from the clinical point of view. It is worth mentioning that, in our study, age was among the most important variables affecting BMI at follow-up that signify more expected weight loss when having surgery at younger age.
In our series, surgery-related mortality and morbidity were 0.9% and 4.7%, respectively. This remarkable accomplishment is primarily due to the introduction of laparoscopic techniques and a long-standing emphasis on safety and quality improvement [15]. In the American College of Surgeons Bariatric Surgery Network database, mortality 30 days after sleeve gastrectomy was 0.11% and Roux-en-Y gastric bypass 0.14%. The 30-day morbidity rate was 5.6% for sleeve gastrectomy and 5.9% for Roux-en-Y gastric bypass [16].
Regarding cardiovascular risk profile, the prevalence of hypertension was 21% with mean systolic and diastolic BP of 127 ± 13.5 and 80 ± 9.5 mmHg respectively. Dyslipidemia was evident in 32% of our patients, and the prevalence of DM was 24% with mean FBS and HbA1c of 99.8 ± 36.8 mg/dL and 5.6 ± 1.1%, respectively.
The prevalence of metabolic syndrome at baseline was 54%. This prevalence was low compared to other studies [17, 18], and this may be explained, at least in part, by the relatively low prevalence of dyslipidemia and hypertension in our study cohort. According to the Framingham risk score to estimate the risk of fatal or nonfatal coronary events in 10 years, risk categories in the current study were low (61.6%), intermediate (9.6%), and high (28.8%). Consistent with our results, in baseline analysis of the recent Traditional Brazilian Diet Trial including 150 adult patients, 55.3% of the study participants were classified as low risk, 4.7% as intermediate risk, and 40.0% as high 10-year CHD risk [19].
Bariatric surgery was associated with significant decrease in BMI after 6 months (45 (43.2–49.3) vs. 32.8 (31.1–35.7) with P value < 0.0001). This was in agreement with previous studies. De La Cruz-Muñoz et al. [20] studied the effectiveness of bariatric surgery in 71 patients. After 1 year, BMI was reduced from 49.7 to 39.2 kg/m2 among males and from 45.1 to 34.4 kg/m2 among females. In another study, Hady et al. [21] studied the impact of laparoscopic sleeve gastrectomy in 100 obese patients with 6 months follow-up period and reported significant reduction of BMI from 52.15 ± 8.5 to 37.98 ± 4.97 kg/m2.
Bariatric surgery was associated with significant improvement in various cardiovascular risk factors after 6 months in our study. The prevalence of hypertension decreased from 21 to 11% (47% remission) with highly significant decrease in systolic blood pressure (P < 0.0001) and diastolic blood pressure (P = 0.0002). In a study by Zhang et al. [22] with a total of 558 patients who underwent either LSG (200) or RYGB (358) for morbid obesity, the prevalence of hypertension was 52% at baseline, and after 6 months follow-up, there was 40% remission of hypertension. Additionally, in the systematic review of Heneghan et al., the prevalence of hypertension was 49% with 68% resolution or reduction in hypertension after a mean follow-up period of 34 months after bariatric surgery [23].
The prevalence of DM decreased from 24 to 12% (50% remission) and additional 16.6% reduction in needed medications. At Cleveland Clinic, 150 obese patients with T2DM were randomized to conventional medical therapy, RYGB, or SG. After 12 months, the primary endpoint which was the proportion of patients achieving HbA1c of 6.0% or less after treatment was achieved in 42% of the RYGB arm, 37% of the LSG arm, and 12% of the conventional medical therapy arm [24]. It is worth mentioning that the 2nd Diabetes Surgery Summit International Consensus Conference published recommendations that bariatric surgery should be considered as a treatment option for patients with T2D [25].
The prevalence of dyslipidemia decreased from 32 to 7% with resolution of dyslipidemia in 78% of our patients. Considerable improvement of all lipid sub-fractions was observed during follow-up in our study. This comes in concordance with Singhal et al. [26] who studied the effect of LSG on lipid profile of 50 obese patients. LSG resolved or improved lipid profile in a majority of patients during initial first 6 months after surgery. In another study, Strain et al. [27] studied 82 patients (67% female, age 46.4 ± 13.9) subjected to bariatric surgery. At 1 year, there was a significant reduction in triglycerides (P = 0.004) and significant increase in HDL (P = 0.025), while total cholesterol and LDL cholesterol showed no significant difference at follow-up. Furthermore, the systematic review of Heneghan et al. [23] came up with concordant results showing 71% resolution or reduction in dyslipidemia.
The prevalence of metabolic syndrome decreased from 54 to 26% at 6 months after bariatric surgery with 52% reduction in its prevalence. Batsis et al. [18] performed a population-based, retrospective study, in which bariatric surgery resulted in 67% reduction in the prevalence of metabolic syndrome. The number of patients with metabolic syndrome decreased from 156 (87%) to 53 (29%) after a mean follow-up of 3.4 years. Silva et al. [17] performed a prospective observational study composed of 96 patients with obesity, among which 86 were women, aged between 18 and 58 years old. At the end of 6 months, bariatric surgery resulted in 80% reduction in the prevalence of metabolic syndrome (69% vs. 14%, P < 0.0001).
At 6 months follow-up, there was a significant decrease in the estimated risk of fatal or nonfatal coronary events in 10 years according to the Framingham risk score (P < 0.0001) and estimated vascular age (P < 0.0001). In a recent study conducted by Blanco et al. [28] involving 360 patients with bariatric surgery, LSG was the most prevalent surgery (63%), followed by RYGB (20.6%), and reported significant reduction of both atherosclerotic cardiovascular disease and Framingham risk scores at 12 months. In another study, Wei et al. [29] recently investigated the benefit of CVD risk reduction after metabolic surgery in 392 obese patients with type 2 DM who had undergone LSG (87) or RYGB (305). The estimated 10-year coronary heart disease risk was reduced from 8.8 to 4.6% (P < 0.001). It is worth mentioning that our study further demonstrated statistically significant positive correlations between Framingham risk score, estimated vascular age, and postoperative 6-month BMI using Spearman’s correlation coefficient.
Electrocardiographic findings at 6 months follow-up revealed significant reduction in resting heart rate and shortening in QTc interval (P < 0.0001 and 0.009, respectively). Owan et al. [30] in the Utah Obesity Study included 423 severely obese patients undergoing bariatric surgery. At a 2-year follow-up, there was a large reduction in heart rate from 74 ± 12 to 60 ± 10. Omran et al. [31] performed a systematic review and meta-analysis of the effects of obesity and weight loss on the corrected QT interval. Weight loss was associated with a significant decrease in QTc (mean difference − 25.77 ms, 95% CI − 28.33–23.21). In another study, Mukerji et al. [32] investigated the effect of weight loss on ventricular repolarization in 39 normotensive morbidly obese patients. Again, weight loss was associated with significant reductions in mean QTc (from 428.7 ± 18.5 to 410.5 ± 11.9 ms, P < 0.0001). LV hypertrophy was a key determinant of QTc interval, and regression of LV hypertrophy related to weight loss was associated with shortening of QTc interval.
Bariatric surgery has been noted to induce changes in heart geometry and function, both systolic and diastolic. In our study, echocardiographic findings at 6 months follow-up revealed significant reduction in LV dimensions and LV mass index (P < 0.0001), increase in LV EF% (P = 0.0003), and increase in E/A ratio (P < 0.0001). Mauricio et al. [33] assessed the effect of BS in 41 patients, and there was a significant reduction in LVMI (101.3 ± 38.34 vs. 86.70 ± 26.65, P = 0.005) and increase in LV shortening fraction (31.05 ± 8.82% vs. 36.34 ± 8.21%, P = 0.007). Aggarwal et al. [34], in their systematic review and meta-analysis of the effect of bariatric surgery on cardiac structure and function, reported significant decrease of both left ventricular mass (mean decrease of 30 g) and mass index (mean decrease of 11%) in addition to significant decrease in LV end diastolic and systolic volumes and significant improvement in ejection fraction. Improvement of diastolic function postsurgical weight loss was also demonstrated by some other studies [35, 36]. It has been postulated that perivascular and interstitial LV fibrosis may contribute to LV diastolic dysfunction in obesity [37]. Our study sheds light on another potential and clinically relevant correlations; postoperative BMI showed significant correlation with LV mass index using Spearman’s correlation and with EF% using multiple regression model.