Bariatric surgery leads to reverse remodelling and improvement in cardiac geometry and function driven by metabolic and haemodynamic factors, according to a systematic review and meta-analysis of studies by researchers from Imperial College London, London, UK.
It is well know that obesity leads to the development of cardiovascular risk factors and disease mortality and the adverse effects of obesity on the cardiovascular system can lead to intrinsic cardiac changes including an increase in left ventricular mass (LVM), left ventricular hypertrophy, and ventricular and atrial dilatations. Such obesity-related structural changes combined with metabolic syndrome can cause impaired cardiac function as a result of maladaptive cardiac remodelling.
According to the researchers, the beneficial effects of bariatric surgery on cardiac structure and function have been demonstrated in several studies. Therefore, though a literature search they sought to quantify the impact of bariatric surgery on changes to cardiac structure and function by synthesising extensive data available in the literature.
They identified 80 studies (54 prospective and 26 were retrospective studies) that included 3,332 patients. The mean age was 42 years with a mean starting BMI of 45.9kg/m2 and the mean follow-up period was 12.2 months. Absolute LVM was reported in 35 studies, which included 2369 patients. Pooled analysis demonstrated a mean decrease of 31.27g in LVM after surgery (p<0.001).
Twenty-two studies including 1,142 patients reported on left ventricular mass index (LVMI) relative to body surface area (m2), analysis showed a decrease after surgery of 10.13% (p<0.001); seven studies including 198 patients, indexed to height (m) showed a decrease of 19.26% (p<0.001) and 16 studies including 1,021 patients indexed to height (m2.7) showed a decrease of 8.66% (p<0.001). Proportional analysis of findings in 45 studies with 2,361 patients demonstrated a weighted mean decrease of 12.2% (p<0.001) in LVMI after surgery.
Sixteen studies including 1,024 patients reported on left ventricular end-systolic volume (LVESV) demonstrating a weighted mean decrease of 7.29 mL (p=0.004) after surgery. Nineteen studies including 1,111 patients reported on left ventricular end-diastolic volume (LVEDV) demonstrating a weighted mean decrease of 14.49 mL (p<0.001) after surgery. Thirteen studies including 539 patients reported left ventricular global longitudinal strain (LVGLS) demonstrating a weighted mean increase of 3.43% (p<0.001).
Twenty-four studies including 993 patients reported on left ventricular systolic dimension (LVSD) pooled analysis demonstrated a decrease of 0.51mm (p<0.001) after surgery. Thirty-eight studies including 2071 patients reported on left ventricular diastolic dimension (LVDD) with analysis demonstrating a decrease of 1.16 mm (p<0.001) after surgery.
The investigated noted that E/A ratio represents the ratio of peak velocity blood flow from left ventricular relaxation in early diastole (the E wave) to peak velocity flow in late diastole (the A wave) caused by atrial contraction [61]. It is therefore a marker of the function of the left ventricle of the heart. Thirty-six studies including 680 patients reported on the E/A ratio before and after surgery, demonstrating an increase of 0.155 (p<0.001).
Twenty-five studies including 1,125 patients reported on left atrial (LA) diameter with pooled analysis demonstrating a decrease of 2.012 mm (p< 0.001) after surgery. Five studies including 209 patients reported on septal E/A ratio with pooled analysis demonstrating a decrease of 0.797 (p<0.001) after surgery.
Forty-three studies including 1,955 patients reported on left ventricular ejection fraction (LVEF) with pooled analysis demonstrating an increase of 1.636% (p< 0.001) after surgery. Eight studies including 676 patients reported on stroke volume (SV) demonstrating a decrease of 2.95 mL (p<0.001) after surgery. Three studies including 151 patients reported on cardiac output demonstrating a decrease of 0.625 mL/min (p =0.089) after surgery.
Resting systolic blood pressure was reported in 24 studies including 1,066 patients. Pooled analysis demonstrated a decrease of 10.918 mmHg (p<0.001) after surgery. Resting diastolic blood pressure was reported in 23 studies including 1,031 patients. Pooled analysis demonstrated a decrease of 5.921 mmHg (p<0.001) after surgery.
Resting heart rate was reported in 12 studies including 554 patients. Pooled analysis demonstrated a weighted mean decrease of 6.68 beats/min (p<0.001) after surgery.
“This meta-analysis and systematic review on the effect of bariatric surgery on cardiac structure and function assessed on cardiac imaging suggests that bariatric surgery is associated with significant improvement in cardiac structure and function” they concluded. “Bariatric surgery can drive reverse cardiac remodelling improving cardiac dysfunction. Further RCTs are justified to describe the relationship between the improvement of cardiac structure and function as assessed by imaging modalities to mortality and morbidity when addressing obesity-associated cardiac disease.”
The outcomes were featured in the paper, ‘The effects of bariatric surgery on cardiac function: a systematic review and meta-analysis’, published in the International Journal of Obesity. To access this paper, please click here