Abstract
Objective
Minimally invasive total arterial coronary artery bypass grafting offers the advantages of total arterial revascularization through an anterolateral minithoracotomy. However, the procedure is technically challenging and associated with a learning curve. The purpose of our study was to evaluate the progress and development of our program over an 8-year period.
Methods
We collected prospective data on all patients who underwent procedure at our institution from January 2015 to December 2023. Our program underwent several modifications during this study period, including optimization of surgical exposure using various available instruments, efficient intraoperative time management, utilization of a standard technique for all off-pump coronary artery bypass procedures, and close team member mentoring. Changes in quality control consisted of transitioning from routine postoperative coronary imaging to clinically indicated imaging. The influence of these interventions was assessed by focusing on in-hospital mortality as the primary end point, and operative time and perioperative myocardial infarction as secondary end points, over 2 time periods consisting of patients operated on during the first and second 4-year study period (Group 1, n = 137 and Group 2, n = 142).
Results
A total of 279 consecutive patients underwent elective, total arterial minimally invasive total arterial coronary artery bypass grafting at our institution over the study period. The mean age of patients was 66 ± 7 years, with 86% being men (n = 241) and 33.1% having diabetes (n = 77). Triple vessel disease was present in 53% of the cohort (n = 123) and left main disease was prevalent in 43% of patients (n = 101). The overall 30-day mortality was 0.4% (n = 1). Compared with the initial 4-year period, the rate of perioperative myocardial infarction decreased 3-fold (4.3% vs 1.4%; P = .1) and there was a statistically significant reduction in operating time (275 ± 59.5 and 246 ± 72.6 minutes; P < .001) in the most recent group of patients.
Conclusions
Total arterial minimally invasive total arterial coronary artery bypass grafting is a feasible surgical approach that can be performed with very good results, even during the initial learning curve phase. An evolving educational program can provide a smooth transition from off-pump coronary artery bypass grafting to minimally invasive total arterial coronary artery bypass grafting, when performed in selected patients in high-volume cardiac centers.
Key Word: minimally invasive coronary surgery
Graphical Abstract
Line chart displaying evolution of MICS-CABG program over an 8-year period.
Central Message.
This study analyzed the results of our MICS-CABG program, comparing the initial with the established phase and demonstrating the safety and evolution of efficacy in our approach.
Perspective.
MICS-CABG offers complete surgical revascularization using both thoracic arteries to multiple distal coronary targets through a small left lateral access. We present our experience and results from both the early and current phases of our program over an 8-year period. Our findings aim to provide centers seeking to establish such a program with the necessary knowledge to implement this in practice.
See Commentator Discussion on page 40.
Coronary artery bypass grafting (CABG) remains among the most prevalent cardiac surgical procedures globally, typically involving a median longitudinal sternotomy. According to the 2018 guidelines of the European Society of Cardiology (ESC), CABG with cardiopulmonary bypass, known as on-pump, is considered the gold standard.1,2 The off-pump coronary artery bypass (OPCAB) procedure is recommended for patients at higher operative risk (Class IIa, Level of Evidence B) and those with a calcified ascending aorta (Class I, Level of Evidence B). However, this procedure should only be performed by skilled surgeons in a specialized center (Class I, Level of Evidence B).1,2 Per the 2018 ESC Guidelines, minimally invasive direct coronary artery bypass (MIDCAB) through a left-sided anterolateral minithoracotomy should be performed in cases of isolated significant stenosis of the proximal left anterior descending artery (LAD) or as a hybrid concept (Class IIa, Level of Evidence B).1,2
The preferred graft material for CABG is the internal thoracic artery (ITA), offering excellent patency rates over the years and ensuring clear long-term survival benefits for patients. Although the use of both internal thoracic arteries (BITA) is associated with better long-term patency rates than the use of left ITA (LITA) plus saphenous vein grafts,3,4 BITA use is also associated with increased risk of sternal wound infection.3, 4, 5, 6
Many investigators are actively assessing strategies to reduce surgical trauma. Surgical trauma is defined by the level of invasiveness, including incision size, involvement of bony structures (eg, sternum), and the use of cardiopulmonary bypass. Therefore, the hypothetical claim that OPCAB minimally invasive total arterial CABG (MICS-CABG) might result in reduced surgical trauma appears to be justified, although this needs further proof.
We performed the first minimally invasive approach for complete arterial off-pump revascularization with BITA through a minimal anterolateral thoracotomy in 2015 at our center.7 Since then, we have established a program to perform this innovative technique in a select group of patients. We herein describe our patient selection, intraoperative setup, in-hospital results, current status, and ongoing evolution and of this technically challenging but promising surgical approach.
Methods
Over an 8-year span from January 2015 to December 2023, a total of 279 consecutive patients underwent MICS-CABG at our institution. We collected prospective data on patient demographic characteristics, preoperative clinical parameters, operative details, and outcome data on all patients. To analyze the evolution of the method over time, we divided our patient cohort into 2 groups. Group 1 (137 patients) consisted of patients who received MICS-CABG from January 2015 to December 2019, and Group 2 (142 patients) underwent the procedure from January 2020 to December 2023. Between January 2015 and December 2023, a total of 7515 isolated CABG procedures were performed at our clinic. The annual distribution of CABG procedures is as follows: 892 in 2015, 873 in 2016, 1012 in 2017, 926 in 2018, 931 in 2019, 772 in 2020, 650 in 2021, 733 in 2022, and 726 in 2023.
The study was approved by the University of Leipzig ethics committee (290/20-ek). Individual patient informed consent was waived due to the retrospective nature of this study.
Patient Selection Criteria
Routine preoperative preparation consisted of a physical examination and medical history, transthoracic echocardiography, 2-view chest radiograph, carotid Doppler examination, electrocardiogram, pulmonary function test, and laboratory tests. In more recent years, we have also performed routine preoperative cardiac computed tomography angiography (CTA). We follow clear patient selection criteria, which have been described in our previous publications.7 To summarize it, 2 major factors are highly relevant: normal cardiac anatomy and sufficient space within the thorax for effective manipulation during the procedure.
All patients with an indication for isolated coronary bypass surgery are potential candidates for MICS-CABG at our center. However, the following criteria were considered for the implementation of the surgical procedure.
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Body mass index <30,
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Adequate lung function (forced expiratory volume in 1 second >50% to 80% of the predicted value or Pao2 >60 mm Hg and PaCo2 <55 mm Hg on room air),
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No pectus excavatum or other severe chest deformations,
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Cardiothoracic ratio (CTR) <50 on chest radiograph or CTA,
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Left ventricular end-diastolic diameter <55 mm,
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No intramuscular or heavily calcified target vessels,
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No acute myocardial infarction in the past 30 days, and
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Availability of a surgeon who is adapt in performing the MICS-CABG technique.
Anesthesia
Ventilation during the operation is performed through a double-lumen tube, which is inserted under bronchoscopic control. Additionally, transesophageal echocardiography is performed to assess the functional status of the heart during the operation, including volume status, newly occurring regurgitation at the mitral and tricuspid valves, and compression of the right ventricle during heart luxation.
Surgical Technique
Our initial surgical technique was detailed in a previous publication (Video 1).7 The following section describes our modifications since then that were intended to simplify the technique and increase its reproducibility within a structured educational program. Our description is based on experience involving the learning curve of 3 surgeons. All surgeons involved in this project possessed extensive experience in OPCAB and MIDCAB, including what is referred to as extended MIDCAB procedures (eg, LAD plus diagonal artery), because we performed very few MICS-CABG procedures during the initial phase. From January 2015 to September 2021, we performed 186 MICS-CABG procedures. From September 2021 to May 2022, no MICS-CABGs were performed. The period from 2020 to part of 2022 was influenced by the pandemic. However, the program was revived, and from June 2022 to December 2023, a total of 93 procedures were conducted. All surgeries were primarily performed by two surgeons. The third surgeon performed fewer than 10 cases.
The number of OPCAB cases alone seems to us to be not sufficient to accurately define a surgeon's proficiency. However, based on our experience, at least 3 to 4 years of regular coronary surgery activity at a high-volume center (meaning a case load of more than 100 cases per year) is essential. But even more important than the regular exposure to the OPCAB procedure might be the variety of OPCAB techniques employed, such as total arterial revascularization; no-touch aorta approach; and proficiency in T-, Y-, and I-graft techniques.
Firstly, we standardized all instruments and stabilizers used for our OPCAB and MIDCAB procedures. For example, only the Octopus Stabilizer (Medtronic) is utilized for all OPCAB, MIDCAB, and MICS-CABG procedures performed at our institution.
Secondly, we started to place the skin incision more laterally compared with our initial approach, with approximately three-quarters of the incision being lateral to the midclavicular line. This positioning provides a more lateral skyline view over the BITA, significantly simplifying the harvesting process and expediting this stage of the operation. The surgical view is good enough to harvest the right ITA (RITA) in its entire length, avoiding the use of a substernal hook (Figures E1 and E2).
Figure E1.
Left internal thoracic artery harvesting.
Figure E2.
Right internal thoracic artery harvesting.
Thirdly, the end-to-side Y- or T-anastomosis between the LITA and RITA is created at the level of the pulmonary valve using 8-0 Prolene (Ethicon) in a continuous suturing technique. The Octopus Stabilizer is used as a support for this anastomosis within the chest cavity, significantly facilitating this technically challenging anastomosis. We pull a gloved finger over the Octopus Stabilizer and secure the LITA to the glove using 6-0 Prolene, ensuring stable, high-quality visualization (Figures E3 and E4).
Figure E3.
Performing T-graft between left internal thoracic artery and right internal thoracic artery.
Figure E4.
Completed left internal thoracic artery/right internal thoracic artery T-graft.
Fourthly, immobilization of the LAD area is now achieved using the Octopus Stabilizer directly, without altering the position of the rib retractor (Figures E5 and E6).
Figure E5.
Completed left internal thoracic artery to left anterior descending artery bypass.
Figure E6.
Flow measurement of left internal thoracic artery to left anterior descending artery graft.
Finally, to facilitate further exposure, the pericardium is opened over the apex of the heart using electrocautery and the incision is extended downward toward the phrenic nerve, allowing heart luxation without hemodynamic compromise and subsequent visualization of the lateral and posterior walls of the left ventricle. The left ventricular apex is luxated upward and in the direction of the incision, and stabilization of the anastomosis area is performed using the Octopus Stabilizer, which is repositioned directly though the main incision. An additional maneuver involves placing a deep suture on the pericardium between the left pulmonary veins, which is then pulled up toward the incision and secured with an additional clamp. No additional suction devices are used for the luxation manoeuvre (Figure E7, Figure E8, Figure E9, Figure E10).
Figure E7.
Luxation manoeuver for lateral wall visualization.
Figure E8.
Exposure and stabilization of the obtuse marginal artery.
Figure E9.
Right internal thoracic artery to obtuse marginal artery grafting.
Figure E10.
Completed right internal thoracic artery to obtuse marginal bypass.
Standardization of Intracoronary Devices and Quality Control
We have also standardized the type of intracoronary shunts (ClearView Shunt; Medtronic) and blower-mister devices (AccuMist; Medtronic) at our center for all OPCAB, MIDCAB, and MICS-CABG operations. Quality control of bypass grafts is performed in all of our patients using transit time flow measurement (QuickFlow DPS System; Medtronic). In all cases with questionable flow parameters (flow <10 mL/minute and/or pulsatility index > 5.0), the anastomosis is revised. After ensuring good anastomosis quality, the heart is carefully repositioned and the pericardium is closed with absorbable sutures without compressing the grafts. Drains are inserted into both pleural cavities and the left lung is inflated under direct visual control. Ribs are adapted using PDS loops (Ethicon; Johnson & Johnson), and local anaesthetic (Naropin; Aspen) is applied in the intercostal space. Subsequently, a layered wound closure and skin sutures are performed.
Postsurgery, patients are transferred to the postanaesthesia care unit and are extubated within 1 to 2 hours. They are then transferred to the stepdown unit, receiving 500 mg intravenous aspirin 4 hours after surgery and starting dual antiplatelet therapy, when indicated, the next day.
We employ the recommendations of the ESC/European Association for Cardio-Thoracic Surgery Guidelines on Myocardial Revascularization as the basis for postoperative dual antiplatelet therapy indication in our center.1 A standardized pain management protocol is implemented for all patients undergoing CABG at our center, aiming to keep the pain rate below 4 on the numeric rating scale. In patients with pain rate higher than numeric rating scale score of 5, patient-controlled analgesia was used.7 For the first 92 patients who underwent MICS-CABG at our center, we performed routine postoperative coronary angiography or CTA for reasons of quality control.7 After we demonstrated very good patency rates for this procedure,7 we switched to performing coronary angiograms only in cases of suspected myocardial ischemia.
Outcomes and Definitions of Explanatory Variables
The primary end point of this study was in-hospital mortality. Secondary end points were length of surgery and perioperative myocardial infarction (PMI).
With regard to explanatory variables, chronic renal insufficiency was graded according to creatinine clearance.8 The definition of acute MI was based on the third universal definition of MI.9 CTR was defined as the ratio of maximal horizontal cardiac diameter to maximal horizontal thoracic diameter (inner edge of ribs/edge of pleura on chest radiograph or CT) × 100.10
Postoperative low cardiac output syndrome definition was defined as follows: Need for mechanical circulatory support with intra-aortic balloon pump, left ventricular assist device, or extracorporeal membrane oxygenation during surgery or within 5 postoperative days (use of mechanical circulatory support was identified by International Classification of Diseases Ninth Edition-Clinical Modification procedure codes), and/or hemodynamic instability requiring continued pharmacologic support with ≥2 inotropic medications (epinephrine or milrinone, dobutamine, or dopamine) on postoperative day 1.11
Statistical Methods
Numerical variables are reported as median with interquartile range (IQR) and were analyzed with Wilcoxon rank sum test or Wilcoxon rank sum exact test, when appropriate. Categorical variables are reported as counts with percentage and were analyzed with χ2 or Fisher exact test. Analyses were performed using the R statistical programming language (R Foundation for Statistical Computing). Continuous normal-distributed variables are reported as mean ± SD and analyzed with t test or analysis of variance. Continuous nonnormal distributed variables are reported as median with first and third quartiles and analyzed with Kruskall-Wallis test. Shapiro-Wilks test is used to decide between normal or nonnormal distributed variables.
Results
All preoperative data are depicted in Table 1. The mean age was 66 ± 7 years, with nearly two-thirds being men and one-third having diabetes. A similar proportion of patients in both groups had triple vessel disease and left main disease. European System for Cardiac Operative Risk Evaluation II (EuroSCORE II) score was higher in Group 1 (median, 1.8 [IQR, 1.2, 2.4] vs 1.1 [IQR, 0.8, 1.8]; P < .001). CTR index, which is commonly used to assess the available space for surgical manipulations in the thorax and reflects the technical complexity of the procedure, was also higher in Group 2 (median, 47.0 [IQR, 44.0; 49.0] vs 48.0 [IQR, 45.0; 51.6]; P = .005).
Table 1.
Baseline characteristics
| Baseline characteristics | MICS-CABG 2015-2019 (n = 137) |
MICS-CABG 2020-2023 (n = 142) |
MICS-CABG total (n = 279) |
P value |
|---|---|---|---|---|
| Age (y) | 67.1 ± 9.3 | 64.8 ± 9.0 | 65.9 ± 9.2 | .03 |
| Male sex | 119 (86.9) | 122 (85.9) | 241 (86.4) | .9 |
| BMI | 26.8 (24.7, 29.1) | 26.9 (24.4, 28.8) | 26.8 (24.5, 29.0) | .9 |
| LV ejection fraction | 60.0 (53, 64) | 57.0 (50, 60) | 58.0 (51.0, 62.0) | .0 |
| Arterial hypertension | 130 (94.9) | 134 (94.4) | 264 (94.6) | .9 |
| Hyperlipidemia | 126 (92.0) | 127 (89.4) | 253 (90.7) | .6 |
| Diabetes mellitus | 49 (35.8) | 45 (31.7) | 94 (33.7) | .5 |
| Current or previous smoking | 42 (30.7) | 59 (41.5) | 101 (36.2) | .07 |
| COPD | 12 (8.7) | 16 (11.3) | 28 (10.0) | .6 |
| Creatinine (mg/dL) | 0.90 (0.79, 1.05) | 0.88 (0.79, 1.01) | 0.90 (0.79, 1.04) | .5 |
| Dialysis | 1 (0.7) | 0 (0.00) | 1 (0.36) | .4 |
| Peripheral vascular disease | 24 (17.5) | 22 (15.5) | 46 (16.5) | .7 |
| Prior cerebrovascular accident | 11 (8.0) | 12 (8.4) | 23 (8.2) | .9 |
| Left main disease | .8 | |||
| 50% | 14 (10.2) | 10 (7.04) | 24 (8.60) | |
| 50%-70% | 17 (12.4) | 18 (12.7) | 35 (12.5) | |
| >70% | 28 (20.4) | 28 (19.7) | 56 (20.1) | |
| Coronary disease details | 1.0 | |||
| 2 vessel disease | 61 (44.5) | 64 (45.1) | 125 (44.8) | |
| 3 vessel disease | 76 (55.5) | 78 (54.9) | 154 (55.2) | |
| EuroSCORE II | 1.82 (1.23, 2.36) | 1.13 (0.80, 1.80) | 1.51 (0.94, 2.08) | <.001 |
| CTR | 47.0 (44.0, 49.0) | 48.0 (45.0, 51.6) | 47.1 (44.0, 50.9) | .005 |
| LVEDD | 47.7 ± 5.29 | 48.6 ± 5.13 | 48.2 ± 5.22 | .1 |
Values are n (%), mean ± SD, or median (25th, 75th percentile). MICS-CABG, Minimally invasive multiple coronary artery bypass grafting; BMI, body mass index; LV, left ventricular; COPD, chronic obstructive pulmonary disease; EuroSCORE II, European System for Cardiac Operative Risk Evaluation II; CTR, cardiothoracic ratio; LVEDD, left ventricular end diastolic diameter.
Intraoperative data are presented in Table 2. Overall, all important segments of the coronary tree were grafted with similar frequency in both groups. Intraoperatively, there were no conversions to sternotomy in either group during the initial operation. The length of the procedure was significantly shorter in Group 2, despite more complex revascularization involving the more frequent grafting of right coronary artery branches and the extension of grafts using short segments of saphenous veins. Sequential anastomoses refer to side-to-side anastomoses using a single graft. More frequent grafting of the right coronary artery has led to greater use of the radial artery for graft extension because the RITA reaches the posterior descending artery only in selected cases. All procedures used 2 grafts. The first cohort had 325 distal anastomoses, and the recent cohort had 330 (2.43 vs 2.31 per patient), with no significant difference between the groups (P = .4).
Table 2.
Intraoperative data
| Intraoperative data | MICS-CABG 2015-2019 (n = 137) |
MICS-CABG 2020-2023 (n = 142) |
MICS-CABG total (n = 279) |
P value |
|---|---|---|---|---|
| Conversion to ONCAB | 4 (2.9) | 0 (0) | 4 (1.4) | .05 |
| Conversion to full sternotomy | 0 (0) | 0 (0) | 0 (0.0) | – |
| Length of surgery (min) | 277 (237, 320) | 246 (200, 298) | 258 (222, 310) | <.001 |
| Grafts | ||||
| BITA | 122 (89.1) | 112 (78.9) | 234 (83.9) | .03 |
| Radial artery | 15 (10.9) | 29 (20.4) | 44 (15.8) | .04 |
| Saphenous vein | 0 (0.0) | 9 (6.3) | 9 (3.2) | .003 |
| No. of distal anastomoses | 325 | 330 | 655 | .4 |
| No. of sequential anastomoses | .2 | |||
| 1 | 87 (63.5) | 103 (72.5) | 190 (68.1) | |
| 2 | 48 (35.0) | 38 (26.8) | 86 (30.8) | |
| 3 | 2 (1.4) | 1 (0.7) | 3 (1.0) | |
| Target vessels | ||||
| LAD | 134 (97.8) | 139 (97.9) | 273 (97.8) | .9 |
| Diagonal branch | 21 (15.3) | 20 (14.1) | 41 (14.7) | .9 |
| Intermediate arteria | 38 (27.7) | 37 (26.1) | 75 (26.9) | .8 |
| LCX/OM | 119 (86.9) | 113 (79.6) | 232 (83.2) | .1 |
| Posterior descending artery | 13 (9.4) | 21 (14.8) | 34 (12.2) | .2 |
Values are presented as n (%) or median (25th, 75th percentile) unless otherwise noted. MICS-CABG, Minimally invasive multiple coronary artery bypass grafting; ONCAB, on-pump coronary artery bypass; BITA, bilateral internal thoracic artery; LAD, left anterior descending artery; LCX/OM, left circumflex artery/obtuse marginal artery.
The use of left radial artery is an additional hurdle for the surgeon due to specific patient positioning (a slight elevation of the left upper body) and generally limited space during the MICS-CABG procedure. Therefore, we rather opt for a saphenous vein extension. In selected cases, the free RITA or a distal LITA segment may be sufficient for posterior descending artery revascularization as an I-graft.
Postoperative outcomes are presented in Table 3. Three patients in Group 1 required a full sternotomy during a coronary revision as a second operation, which was not observed in Group 2. One patient from Group 1 died during the in-hospital period on the day of discharge due to sudden cardiac death, resulting in an overall in-hospital mortality rate of 0.4%.
Table 3.
Postoperative outcomes
| Postoperative outcomes | MICS-CABG 2015-2019 (n = 137) |
MICS-CABG 2020-2023 (n = 142) |
MICS-CABG total (n = 279) |
P value |
|---|---|---|---|---|
| In hospital mortality | 1 (0.7) | 0 | 1 (0.4) | – |
| Low cardiac output | 3 (2.2) | 1 (0.7) | 4 (1.4) | .3 |
| ECLS | 1 (0.7) | 0 (0.0) | 1 (0.3) | .4 |
| Secondary conversion to sternotomy | 3 (2.1) | 0 (0.0) | 3 (1.0) | .7 |
| Perioperative myocardial | 6 (4.3) | 2 (1.4) | 8 (2.8) | .1 |
| Unplanned postoperative CA | 9 (6.6) | 6 (4.2) | 15 (5.3) | .4 |
| Conservative: Good result | 3 (2.2) | 2 (1.4) | 5 (1.8) | .6 |
| Bypass revision | 3 (2.2) | 3 (2.1) | 6 (2.1) | .9 |
| Unplanned postoperative PCI/stenting | 5 (3.6) | 0 (0.0) | 5 (1.7) | .3 |
| Rethoracotomy for bleeding | 9 (6.6) | 4 (2.8) | 13 (4.0) | .2 |
| Need for postoperative dialysis | 3 (2.2) | 1 (0.7) | 4 (1.4) | .3 |
| Wound infection | 1 (0.7) | 2 (1.4) | 3 (1.0) | .6 |
| Highest postoperative CK-MB (U/L) | 34 (25.0, 50.0) | 32.4 (24.6, 43.0) | 33.0 (25.0, 47.5) | .3 |
| Incomplete revascularization | 7 (5.1) | 3 (2.1) | 10 (3.5) | .9 |
| Planned postoperative CA | 72 (52.6) | 20 (14.1) | 92 (33.0) | <.001 |
| Tracheotomy | 3 (2.2) | 6 (4.2) | 9 (3.2) | .5 |
Values are presented as n (%) or median (25th, 75th percentile). MICS-CABG, Minimally invasive multiple coronary artery bypass grafting; ECLS, extracorporeal life support; CA, coronary angiography; PCI, percutaneous coronary intervention; CK-MB, creatine kinase-MB.
Routine postoperative coronary angiography or CTA was performed in the first 92 consecutive patients. The graft patency rate in these patients was 96.8%. Our initial protocol included postoperative coronary angiography during the same hospital stay as a standard of care.7
A total of 16 patients (5.7%) exhibited elevated serum creatine kinase-MB (CK-MB) level or other clinical signs suggestive of myocardial ischemia. Of them, 10 (7.2%) patients in Group 1 exhibited elevated serum CK-MB levels and/or electrocardiogram changes suggestive of postoperative myocardial ischemia. Among these, 6 patients (4.3%) were confirmed to have experienced PMI.9 Planned and unplanned coronary angiography in Group 1 revealed early graft dysfunction in 11 patients (8.0%). Of these, 5 patients (3.6%) had anastomotic/graft issues involving the obtuse marginal (3 patients) and posterior descending arteries (2 patients) and underwent percutaneous coronary intervention, whereas 3 patients (2.1%) required surgical graft revision.
In Group 2, a total of 5 patients had postoperative CK-MB elevation or other clinical signs suggestive of myocardial ischemia. Two of these patients (1.4%) met the criteria for PMI without angiographic correlation. Among the other 3 patients, 1 patient had a pathologic angiography showing 40% to 50% stenosis of the LITA graft that did not require surgical correction and the other 2 patients’ angiography was unremarkable.
Additionally, 2 patients (1.4%) presented with ventricular extrasystoles and nonsustained ventricular tachycardias, with no other electrocardiogram changes and no CK-MB/troponin level elevation and underwent unplanned angiography. Pathological findings were detected in both cases: 1 with kinking of the bypass to the posterolateral artery and the other with a LITA bypass to a small LAD. Both patients were treated with surgical revision, but these patients did not meet criteria for PMI.9
Overall, in Group 2, we observed 3 cases necessitating bypass revision. In the first patient, kinking of the RITA to the posterolateral artery was resolved surgically. In the second case, the dominant diagonal artery was additionally grafted because of small diameter of the LAD. The third patient exhibited thrombus formation in the RITA intraoperatively during the RITA to obtuse marginal anastomosis. An immediate postoperative coronary angiography was performed due to unexplained clinical findings, raising suspicion of T-graft narrowing caused by a clip; however, this was not confirmed during revision. In Group 2, 3 patients (2.1%) experienced incomplete revascularization, attributed to small calcified and nongraftable right coronary artery. Additionally, 3 patients (2.1%) underwent planned hybrid procedures with percutaneous coronary intervention performed as a second stage.
Compared with the initial 4-year period of our study, the rate of PMI decreased 3-fold in Group 2 (4.3% vs 1.4%; P = .1). Another important observation is that revision for bleeding rates were numerically lower in Group 2.
Discussion
The current article reports on our evolution of the MICS-CABG procedure in terms of surgical techniques, clinical setup, and perioperative results over a period of 8 years. Since its implementation, our MICS-CABG program has undergone continuous improvement through a heart team-based patient selection and standardization of several aspects of the surgical procedure. It was therefore the purpose of our study to analyze the influence of the advancements and modifications made to the procedure on clinical outcomes.
Modifications of our surgical setup consisted of a more lateral incision, avoiding the use of a substernal hook, standard utilization of the Octopus Stabilizer for all off-pump procedures (OPCAB, MIDCAB, and MICS-CABG) at our institution, and the application of deep pericardial sutures for heart rotation and exposure. A more lateral incision, as described by McGinn and colleagues7,11 was a logical progression in our early experience, providing the surgeon with better exposure. We how use the heart luxation technique, logically adopted from OPCAB to MICS-CABG, to simplify the entire procedure. Heart luxation techniques, which avoid suction devices and utilize pericardial sutures, have been detailed by Babliak and colleagues.9,12 The total operation time of approximately 3 hours in our latest period is significantly shorter compared with our initial experience, and is similar to that described by Babliak and colleagues.13 We believe this is the result of all the above-described modifications, particularly the standardization of intraoperative equipment and methods.
We have also modified our preoperative assessment to include a CTA to rule out intramyocardial vessels, heavy coronary calcifications, and pulmonary adhesions. The CTA therefore allows us to obtain comprehensive details about the coronary anatomy, which has been described by other investigators (Figure E11).14, 15, 16 CTA has also been described as a method to assess postoperative patency of grafts after the MICS-CABG procedure.17
Figure E11.
Preoperative computerized tomography scan.
We have previously reported our initial experience with total arterial off-pump MICS-CABG exclusively using BITAs, showing comparable 30-day mortality rates after OPCAB performed through sternotomy by expert surgeons.7,18, 19, 20 The in-hospital mortality of the current study consisted of only 1 patient (0.4%) who died during our very initial experience. These results are comparable with the 3 largest MICS-CABG series published to date.12,13,21 The significantly lower EuroSCORE II in the most recent group obviously reflects our meticulous patient selection practice. Hereby, the selection criteria are rather based on anatomical, than clinical aspects of the candidates: normal cardiac anatomy and sufficient space within the thorax for effective manipulation during the procedure. This anatomical selection results in a patient cohort with a lower EuroSCORE score.
The rate of surgical revision for graft failure remained unchanged during the time period of our study and is comparable to that reported by other researchers.11, 12, 13 It showed a nonsignificant trend toward the reduction of PMI (4.3% vs 1.4%; P = .1) and bleeding complications (6.6% vs 2.8%; P = .2) in the last group, which, due to the small sample size and the observational nature of the study, does not allow for any definitive conclusions to be drawn.
The prevalence of complications in the current study, including stroke and chest wound infections, aligns with our early experiences. Literature indicates that the stroke rate following isolated CABG ranges from 0.6% to 4.0%.7,22,23 Notably, no patient in our MICS-CABG program developed an embolic stroke. This outcome is likely attributable to the avoidance of aortic manipulation during the procedure and a lower incidence of atrial fibrillation (18.8%), a finding corroborated by other MICS-CABG studies.12 We observed only 1 stroke in the current study, which was attributed to a prolonged low-flow phase induced by hemorrhagic shock from a bleeding RITA vein, as documented during our initial publication.7
The training of young surgeons in the MICS-CABG procedure is a highly debated topic due to the procedure's challenging nature. Several factors contribute to this difficulty: the limited view through the small incision, the technically challenging harvesting of BITA, and the complex luxation techniques required. In our clinic, we have developed the following educational concept that may facilitate a transition from on-pump CABG to OPCAB, then to MIDCAB, and finally to MICS-CABG for advanced coronary surgeons. The similar stepwise approach for gaining experience in learning MICS-CABG has been advocated by other surgeons.18,24, 25, 26 In particular, we found the Indian experience very sophisticated, which was based on a brief questionnaire of surgeons who performed MICS-CABG. Of these, 69% had performed minimally invasive surgery before starting the MICS-CABG procedure.25, 26 Undoubtedly, this has a significant influence on the surgical mindset and capabilities. Definition of the time range and number of performed cases under close mentorship are still a matter of debate.24 Typically, after gaining substantial experience in OPCAB surgery, surgeons transition to MIDCAB and regular assisting in MICS-CABG procedures. Once proficient in LITA harvesting, they begin RITA harvesting in anatomically suitable cases. The performance of Y- or T-graft anastomoses, LITA to LAD anastomoses and, finally, RITA to posterolateral artery or (even more advanced) right coronary artery end-branch anastomoses in suitable anatomy are the next steps.
Study Limitations
Our study, despite being retrospective and involving the learning curve of 3 surgeons, provides valuable insights. It is important to consider the specialized nature of this procedure, performed by a limited number of surgeons on carefully selected patients. This observational study primarily aimed to illustrate the developmental process of establishing the method. Given the small number of cases/events, it is underpowered to thoroughly assess midterm mortality and major adverse cardiac and cerebrovascular events, which is a key limitation of the data. Thus, broad generalizations to all surgeons and patient populations should be approached with caution. Nonetheless, the outcomes demonstrate the potential of this technique in specialized, high-volume center.
Conclusions
Total arterial MICS-CABG is a feasible, but technically challenging, surgical procedure yielding very good results in a structured program. Standardization of equipment and techniques, along with evolving educational aspects, may provide a smooth transition from OPCAB to MICS-CABG for advanced coronary surgeons, when performed in selected patients in specialized high-volume centers.
Webcast
You can watch a Webcast of this AATS meeting presentation by going to: https://www.aats.org/resources/minimally-invasive-coronary-ar-7113.
Conflict of Interest Statement
The authors reported no conflicts of interest.
The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest.
Supplementary Data
A 5-7 cm incision is made in the fifth intercostal space at the midclavicular line, with one-third of the incision medial to the line and the remaining two-thirds lateral to it. This provides the necessary skyline view for the skeletonized preparation of the bilateral internal thoracic arteries using a diathermy blade. The intercostal space is retracted using the Galgen retractor, with the blade oriented parallel to the course of the internal mammary artery to avoid injury. A gloved Octopus stabilizer ensures a stable field for constructing the composite conduit between both internal thoracic arteries, which is performed using an 8-0 Prolene suture. The grafting procedure then follows our standard off-pump coronary artery bypass approach, utilizing a shunt and the Octopus stabilizer. We always begin by grafting the left internal thoracic artery to the left anterior descending artery. For grafting the lateral and posterior walls, the pericardium is opened, extending to the inferior vena cava on the right and beyond the left ventricular apex on the left. One or 2 pericardial stay sutures may be used to optimize exposure. The obtuse marginal artery is then grafted using the right internal thoracic artery conduit. After completing the grafting, protamine is administered, 2 pleural drains are placed, and the wound is closed in the usual manner. Video available at: https://www.jtcvs.org/article/S2666-2507(24)00456-5/fulltext.
Appendix E1
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
A 5-7 cm incision is made in the fifth intercostal space at the midclavicular line, with one-third of the incision medial to the line and the remaining two-thirds lateral to it. This provides the necessary skyline view for the skeletonized preparation of the bilateral internal thoracic arteries using a diathermy blade. The intercostal space is retracted using the Galgen retractor, with the blade oriented parallel to the course of the internal mammary artery to avoid injury. A gloved Octopus stabilizer ensures a stable field for constructing the composite conduit between both internal thoracic arteries, which is performed using an 8-0 Prolene suture. The grafting procedure then follows our standard off-pump coronary artery bypass approach, utilizing a shunt and the Octopus stabilizer. We always begin by grafting the left internal thoracic artery to the left anterior descending artery. For grafting the lateral and posterior walls, the pericardium is opened, extending to the inferior vena cava on the right and beyond the left ventricular apex on the left. One or 2 pericardial stay sutures may be used to optimize exposure. The obtuse marginal artery is then grafted using the right internal thoracic artery conduit. After completing the grafting, protamine is administered, 2 pleural drains are placed, and the wound is closed in the usual manner. Video available at: https://www.jtcvs.org/article/S2666-2507(24)00456-5/fulltext.