Between January 2010 and December 2018, 1290 patients with class II/III obesity underwent primary bariatric surgery at our institution. Before surgery, 258 (20%) had a DM diagnosis and were included in this analysis. Three patients (1.2%) had DM type 1, and the remaining 255 patients had T2DM. In 200/258 patients (77.5%), the mean duration of diabetes was 7.9 (±7.4) years. In 58 patients, the duration of diabetes was not documented. The median Body Mass Index (BMI) at time of operation was 42 kg/m2 (±6.9), 80 (33%) patients were obesity class II and 178 (67%) class III, 48.1% were female, mean age was 52.7 years, and median HbA1c was 7.1% (±1.32). Cardiovascular comorbidities presented before screening were dyslipidemia in 219 (84.9%) patients, obstructive sleep apnea (OSA) in 99 (38.4%) patients, and arterial hypertension in 215 (83.3%) patients. Arterial hypertension was treated with medication in 207 patients (96.3% of 215), OSA was treated (e.g., continuous positive airway pressure) in 75 patients (75.8% of 99 patients), and dyslipidemia was treated in 137 patients (62.6% of 219). Complications of diabetes were neuropathy in 15 (5.8%), nephropathy in 11 (4.3%) patients, and known coronary heart disease in 17 (6.6%) patients. Retinopathy was not evident in any patient. Diabetes was not treated medically but using lifestyle-modifications (e.g., exercise and diet) in 33 patients (12.8%) (Table 1).
A total of 246 of the 258 patients (95.3%) received preoperative cardiac diagnostics. One hundred seventy-three (67.1%) underwent stress-rest myocardial perfusion imaging. Nine (3.5%) patients did not receive an MPS due to technical limitations (weight >180 kg) or patients’ inability to perform MPS; instead, they underwent echocardiography and stress electrocardiography. A total of 58 (22.5%) patients received echocardiography and stress electrocardiography. Fifteen (5.8%) patients had had other recent cardiac imaging including diagnostic coronary angiography. Three patients (1.2%) were referred directly to cardiac catheterization due to clinical presentation. A total of nine (3.5%) patients had no specific cardiac workup before surgery as they were young (<30 years) and had a duration of type 2 diabetes of less than 1 year.
As a consequence of the before mentioned diagnostic procedures, cardiac catheterization was performed in a total of 28 patients (10.9% of 258 patients) before bariatric surgery. Of those patients, 24 (85.7% of 28 patients) received cardiac catheterization due to MPS findings. In one (3.6%) patient, pathological echocardiography and a treadmill-test were the indication, and in three (10.7%) patients, cardiac catheterization was performed due to clinical presentation during routine preoperative workup. Cardiac catheterization was scheduled timely, and delay to bariatric surgery was 4 (cardiac catheterization) to 6 weeks (coronary artery bypass surgery).
A significant cardiovascular disease could be ruled out in 13 of the 28 patients who underwent cardiac catheterization. Five patients were newly diagnosed with diffuse vascular sclerosis but no relevant stenosis. Eight patients underwent coronary angioplasty and stenting, and two patients underwent coronary artery bypass surgery (Fig. 1). In patients with a diagnosed CHD, 2 (15.3%) were never-smokers, 5 (33.3%) were active smokers, and 8 (53.3%) smoked in the past.
The overall number needed to screen (= NNS) to detect one CHD was 17.2. Thereof, CHD was detected in 12 patients due to findings in the MPS (NNS 17). One patient with CHD was detected due to pathological TTE/Ergometry findings (NNS 58), and three patients with CHD were detected due to clinical presentation prior to cardiac catheterization. One patient with an already known CHD (one-vessel disease) underwent cardiac catheterization with angioplasty and stenting due to pathological findings in the MPS, resulting in the diagnosis of a two-vessel disease.
Laparoscopic Roux-en-Y gastric bypass was performed in 164 (63.6%) patients, and 94 (36.4%) received sleeve gastrectomy. In none of our patients, bariatric surgery had to be cancelled due to preoperative diagnostics, and bariatric surgery could be performed without any inhouse perioperative cardiovascular events. One patient (0.4%) died of an unknown cause at home 7 days after surgery. Relatives denied an autopsy. The preoperative diagnostics in this patient included an echocardiography and an ECG stress-test, both without pathological findings. Known comorbidities in this patient were arterial hypertension, OSA, and dyslipidemia. Another patient suffered from a transient ischemic attack (0.4%) perioperatively. Preoperative echocardiography and an ECG stress test in this patient had been without pathological findings. Known comorbidities were arterial hypertension, OSA, and dyslipidemia.
Estimated costs of the diagnostic procedures in Switzerland are as follows: The MPS with rest and pharmacological induced stress test costs around 2700 United States Dollars (USD). An ECG stress-test and transthoracic echocardiography are approximately 150 USD and 400 USD, respectively. In total, 173 MPS and 58 echocardiography plus ECG stress-test were performed to detect 15 cases of newly diagnosed CHD. The overall costs of our preoperative cardiac diagnostics in our cohort are therefore around 2000 USD per patient with class II/III obesity and diabetes.