**5. Surgical ventricular restoration (SVR) (Dor procedure)**

Although SVR, also called the Dor procedure, is not a revascularization procedure per se, coronary surgeons are frequently consulted for patients with ischemic cardiomyopathy with a low EF. It is common to evaluate patients with a dyskinetic or akinetic apex, anterior wall, or distal septum after a STEMI involving the LAD. Frequently, isolated left ventricular dysfunction occurs.

Left ventricular remodeling is responsible for left ventricular dilatation, which is quantified by left ventricular end-diastolic volume (LVEDV), left ventricular endsystolic volume (LVESV), left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), and the corresponding indices. In ischemic cardiomyopathy with low EF, these measures demonstrate a dilated, ineffective left ventricle. Congestive heart failure, low cardiac output, and ventricular arrhythmias are common sequelae of left ventricular remodeling.

Patients with ischemic cardiomyopathy with depressed EF benefit from surgical revascularization of viable territories in addition to the removal of the infarcted area and surgical ventricular restoration. The affected area may be aneurysmal. SVR decreases ventricular volume and increases EF, making the left ventricle more conical in shape and efficient, as the viable myocardium is revascularized. SVR is different from LV aneurysm repair, but both are operations that fall under the category of ventricular volume reduction operations. These techniques are frequently combined with the IABP and Impella® devices for hemodynamic support in the perioperative period. The STICH trial compared CABG + SVR vs. CABG alone [57]. Although this study showed no differences between these two techniques [57], in expert hands, patients undergoing CABG + SVR have improved, event-free survival (**Figure 7**).

**Figure 7.** *The Dor procedure.*

### **6. Diabetic patients**

Since hypothesis-generated data emerged from the Bypass Angioplasty Revascularization Investigation (BARI) trial [58], CABG has been the preferred revascularization approach in diabetic patients with advanced CAD. Approximately 40% of all patients undergoing coronary revascularization have diabetes [59]. Rates of arteriolosclerosis are higher among diabetic patients because of the nature of the disease (proliferation, inflammation) and the prothrombotic nature of diabetes. As a result, diabetic patients are more likely to have complex, multivessel CAD involving large territories of the myocardium. Both the Future REvascularization Evaluation in patients with Diabetes Mellitus (FREEDOM) and SYNTAX trials found CABG to outperform PCI in this patient population [7, 60, 61]. The Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) trial found reduced cardiovascular events with CABG compared to GDMT [62]. Higher rates of repeat revascularization were found in diabetic patients who initially underwent PCI. Overall, diabetic patients experience higher mortality and cardiovascular complications when treated with PCI [63]. This finding can be partially explained by the diffuse nature of CAD in diabetic patients, making CABG a better intervention to achieve complete revascularization.

Diabetic patients are also prone to wound infection, impaired wound healing, and renal complications [7, 64]. In terms of the approach for CABG, bilateral IMA grafting is very selectively recommended due to high rates of wound infection. In summary, the SYNTAX, BARI 2D, and FREEDOM trials support CABG for diabetic patients with multivessel CAD [7, 60, 62]; CABG is associated with better outcomes, as the underlying disease pathophysiology is more extensive. In addition, a more complete revascularization is obtained via CABG, resulting in better outcomes. Capitalizing on the LIMA-to-LAD anastomosis is critical in reaping the benefits of CABG in diabetic patients.

### **7. Simulation training**

Simulation has assumed a more significant role in medical education and surgical training. An exceptionally high level of expertise and skill is required to perform the previously discussed complex coronary operations. An increasing number of general surgery and cardiothoracic surgery training programs have incorporated surgical simulations of various modalities into their programs. Wet labs, virtual reality platforms, robotic training, and didactics are central to enhancing the trainees' technical skills and clinical knowledge before progressing to surgery in the clinical realm. Senior cardiac surgeons, professors, and mentors are key elements in this process.

The benefits of simulation training are widely documented, as there is no risk to patient safety, and learners are allowed to practice high-acuity, technically demanding procedures in a safe yet controlled environment. Simulation enables learners to practice technical skills unique to cardiac surgery while gaining direct exposure to and an appreciation for the art of cardiac surgery. More recent literature is now showing how simulation training modalities increased engagement with and knowledge of cardiac surgery procedures [65]. A high faculty-to-learner ratio and hands-on experiences were among some of the factors that contributed to learner satisfaction with simulation training [65].

Increasing exposure to cardiac operations early in training via simulation education is vital in increasing interest in and engagement with cardiac surgery as a field. Studies suggest cardiac surgeons choose subspecialty early in residency, if not in

medical school. Medical students and junior residents are the ideal target population for recruiting future cardiac surgeons.

### **8. Conclusions**

Coronary artery revascularization has experienced significant improvements since the first CABG was performed. The advent of PCI and DES have significantly contributed to the interventional care of patients with CAD. However, CABG remains the preferred revascularization technique for patients with advanced CAD.

The LIMA-to-LAD graft and the completeness of revascularization (not affected by the SYNTAX Score) are highly responsible for most of the long-term benefits of CABG. As the field of coronary surgery moves into the era of minimally invasive approaches, MIDCAB, MICS, robotic cardiac surgery, and OPCAB offer less invasive options to minimize the morbidity associated with traditional on-pump, trans-sternal CABG while preserving the benefits of the traditional operation. Using the RIMA and radial arteries as additional arterial grafts, as opposed to saphenous veins, in addition to the LIMA, extends the long-term benefits of bypass surgery.

Coronary endarterectomy and TMR complement the final treatment of the patients who are screened for CABG. Operations that treat the sequela of ischemic heart disease, including SVR (Dor Procedure) and LV aneurysm repair, are valuable surgical options for patients with ischemic cardiomyopathy. Mechanical complications of STEMI still require repair of the underlying mechanical problem, such as interventricular septal rupture, ventricular free wall rupture, and acute mitral regurgitation secondary to papillary muscle rupture. Multimodal simulation allows trainees and experienced surgeons to train for high-complexity coronary operations, minimally invasive approaches, and other high-acuity operations without compromising patient safety.

## **Acknowledgements**

**Figures 2**–**6** created with BioRender.com.
