Consider bariatric surgery in obese patients

Background

Body mass index - the easy measure of weight in kilograms divided by the square of the height in metres - is the single main criteria driving the decision to perform bariatric surgery, an intermediate-risk noncardiac intervention (1) that promotes weight loss by changing the digestive system's anatomy. For a review of the effects of obesity on health, lifestyle modifications and medical treatment needed for obese patients and description of bariatric surgery, view previous article by same authors. 

I - Guidelines and Role of Cardiologist

Current guidelines include a cardiovascular (CV) evaluation of all prospective candidates as an integral part of preoperative management. Furthermore even though results and complication rates are similar for patients with or without CV disease (2,3) if a patient is confirmed to have a CV disease 1) extensive preoperative investigation using various tests to assess risk is necessary and 2) an adjusted drug regimen is in order. Lastly, in the severely obese, a cardiologist should be present on the multidisciplinary team that manages the intervention.

II - Indications and Tools

Severely obese patients carry a high risk of several diseases, cardiovascular (CV) events being among the most relevant (Table 1). (4) Bariatric surgery, by improving most of CV risk factors, lowers the risk of most cardiac and cerebrovascular events (5) (Figure 1). Indications are that surgery be performed in patients:

1. Over 40 kg/m² 
2. Between 35 and 40 kg/m² - when CVD or other obesity-related comorbidities are present 
3. Between 30 and 34,9 kg/m² - in non-compliant patients with diabetes or metabolic syndrome (6)

Contraindications are that surgery not be performed in patients with:

1. Recent acute myocardial infarction - due to increased complication rate and lower success rates in such cases.
2. Severe respiratory, renal, or hepatic insufficiency, drug and alcohol abuse or unstable psychological/psychiatric reasons - due to probable interference with the adherence to the necessary postoperative care that are follow-up visits and tests, lifestyle, medical management. (7)

The Revised Cardiac Risk Index (8) can be applied to this intervention as any major surgical procedure. It includes six independent prognostic factors: high risk intervention (including intra-abdominal), history of coronary disease, past or present heart failure, stroke, diabetes needing insulin (withdrawn from the simplified index in 2013) (9), and creatinine over 2.0 mg/dL. This score has been slightly improved adding new parameters, such as sensitive troponin elevation. (10)   
The American College of Surgeons score (NSQIP) was developed primarily for bariatric surgery and includes peripheral artery disease, shortness of breath at baseline, previous coronary revascularisation, age, initial BMI, chronic steroid therapy, and type of bariatric intervention (percutaneous vs. not). (11).

III - Preoperative Practice

A - Testing

History, physical examination, and a resting 12-lead electrocardiogram are always carried before surgery. However whether echocardiography, new technological ultrasonic approaches, or stress testing is varies.

• Echocardiography: is usually performed, especially in patients with CV history or symptoms or suspicion of pulmonary hypertension and new technological ultrasonic approaches have been added to conventional two-dimensional Doppler echocardiography aimed to detect structural changes in the heart after bariatric surgery rather than to assess CV disease. (12)

Stress testing before intermediate-risk interventions - such as bariatric surgery - has received a weak recommendation (grade IIb, C) in European guidelines on preoperative evaluation. (13)
Other imaging tests are indicated on an individual basis. 
The methods for preoperative CV risk assessment before bariatric surgery found in a recent systematic literature search are also diverse:

• Noninvasive provocative testing: is usually performed under pharmacologic stress (dobutamine) because severely obese patients are mostly unfit and unable to exercise.

• Magnetic resonance images are useful to assess cardiac anatomy and function both before and after the operation.(15)

• Coronary artery calcium scores and computed tomography coronary angiography have proven useful to predict post-operative CV events in patients undergoing intermediate-risk surgery. (16) These tools have been used for the preoperative assessment of patients undergoing bariatric surgery to detect significant coronary stenosis. (17)

B - Revascularised Patients

Revascularised patients can safely undergo the surgery provided the recommended delays are respected: minimum 6 weeks and optimally 3 months following bare metal stent implantation; 12 months following drug-eluting stent implantation; at least 2 weeks following balloon angioplasty; and a minimum of 3 months and optimally 6 months after successful bypass operation. 

C - Drug Regimen

 1) Beta-blockers

Perioperative beta-blockers are commonly prescribed for patients with CV disease or abnormal tests, although the evidence in severely obese patients is scarce. Moreover, European guidelines on this topic rely on evidence that has come from a single centre, whose validity has been questioned. There is no reason to initiate a beta-blocker before operating in patients who have no other indication for such a drug. Nevertheless, patients on beta-blockers should continue treatment. In a registry of 8,431 patients undergoing elective colorectal and bariatric surgical procedures - 23.5% of whom were taking beta-blockers prior to surgery - beta-blocker continuation on the day of and after surgery was associated with fewer cardiac events and a lower 90-day mortality. (19) 

2) Thrombophylaxis

Thromboprophylaxis is indicated. Main therapies for that purpose are low-molecular weight heparin and mechanical devices. There is no indication for temporary inferior vena cava filters. (20) Antiplatelet therapy should not be started before operation, but patients taking aspirin do not need to withhold their treatment; clopidogrel is to be discontinued 1 week before operation.

3) Antidiabetics

Patients taking oral antidiabetic drugs can continue, except for secretagogues. Insulin therapy can be started according to local rules for elective operations in diabetic patients.

 IV - Results and Costs

Mortality and morbidity related to bariatric surgery are continuously improving and depend mainly on the surgical technique applied and the experience of the team. Mortality rates range from 0.05 to 0.26%, reoperation rates from 1.6 to 3.4 % and total morbidity rates from 5.2 to 14.5%.
Bariatric surgery improves many obesity-associated comorbidities and saves costs because obese patients consume 20% less health resources and 68% fewer drugs. As a consequence, the initial costs (7,468 €) become net savings by the third year (apart from supplementary not-counted savings due to the increase in tax incomes from a 57% increase in work productivity for professionals and a 18% reduction in sick leaves. (21) 
A recent evidence-based review in patients with diabetes showed that bariatric surgery increased both quality-adjusted life years (QALYs) and costs. Cost-effectiveness ratios for severely obese patients with established diabetes were $12,000 per QALY for bypass surgery and $13,000 per QALY for gastric banding. (22)  
Trying to find out the reimbursement policies of this surgery across European countries has been an excessive challenge. We ask the ESC e-journal readers to contribute their input to lighten this issue by writing your comment in a tweet. 

Conclusions

Here is a review the main points discussed in this article:

• Body mass index, an easy measure within the reach of all physicians, is the single criteria driving the decision to send a patient for bariatric surgery. Provided there are no contraindications, all patients above 40kg/m2 and those between 35-40kg/m2 should be considered for bariatric surgery. 
• Cardiologists can help in pre-operative assessment, in adapting drug regimens in CVD patients and by being part of the multidisciplinary team to manage the surgical procedure of the severely obese.  History, physical examination, and a resting 12-lead electrocardiogram are always carried out, echocardiography, new technological ultrasonic approaches, or stress testing will depend on the case and centre. Previous revascularisation is not a problem for prospective interventions.
• Bariatric surgery improves diabetes by 80%, sleep apnea, CV diseases; hypertension by 65% and mortality by 30-40%. 
• The initial costs (7,468 Euros) of bariatric surgery have been shown to become net savings by the third year. We encourage cardiologists to consider obese patients for bariatric surgery. 

In all, we encourage cardiologists to consider obese patients for bariatric surgery.