Twenty-Year Experience With Off-Pump Coronary Artery Bypass Grafting and Early Postoperative Angiography

Impact of Myocardial Viability on Long-term Outcomes after Surgical Revascularization

BACKGROUND

 This study was conducted to evaluate whether myocardial viability assessed with cardiac magnetic resonance (CMR) affected long-term clinical outcomes after coronary artery bypass grafting (CABG) in patients with ischemic cardiomyopathy (ICMP).

METHODS

 Preoperative CMR with late gadolinium enhancement (LGE) was performed in 103 patients (64.9 ± 10.1 years, male:female = 82:21) with 3-vessel disease and left ventricular dysfunction (ejection fraction ≤ 0.35). Transmural extent of LGE was evaluated on a 16-segment model, and transmurality was graded on a 5-point scale: grades-0, absence; 1, 1 to 25%; 2, 26 to 50%; 3, 51 to 75%; 4, 76 to 100%. Median follow-up duration was 65.5 months (interquartile range = 27.5-95.3 months). Primary endpoint was the composite of all-cause mortality or hospitalization for congestive heart failure.

RESULTS

 Operative mortality was 1.9%. During the follow-up, all-cause mortality and readmission for congestive heart failure occurred in 29 and 8 patients, respectively. The cumulative incidence of the primary endpoint was 31.3 and 46.8% at 5 and 10 years, respectively. Multivariable analysis demonstrated that the number of segments with LGE grade 4 was a significant risk factor (hazard ratio 1.42, 95% confidence interval 1.10-1.83, p = 0.007) for the primary endpoint among the variables assessed by CMR. Other risk factors included age, dialysis, chronic obstructive pulmonary disease, and EuroSCORE II.

CONCLUSION

 The number of myocardial segments with transmurality of LGE >75% might be a prognostic factor associated with the composite of all-cause mortality or hospitalization for congestive heart failure after CABG in patients with 3-vessel disease and ICMP.

Impact of Functional vs Anatomic Complete Revascularization in Coronary Artery Bypass Grafting

BACKGROUND

This study was conducted to evaluate the impact of functional and anatomic complete revascularization on long-term clinical outcomes after coronary artery bypass grafting (CABG).

METHODS

Of 2034 patients who underwent primary isolated CABG between 2006 and 2017, 1162 patients who underwent off-pump CABG for 3-vessel disease and for whom data on functional and anatomic completeness of revascularization were available on the basis of preoperative myocardial single photon emission computed tomography and early postoperative graft angiography were enrolled. The median follow-up duration was 82.4 months (interquartile range, 50.8-122.4 months). Univariate and multivariate analyses were performed to evaluate the impact of the functional and anatomic completeness of revascularization on long-term survival.

RESULTS

Of 1162 patients, anatomic complete revascularization was achieved in 1014 patients (87.3%), whereas functional complete revascularization was achieved in 1077 patients (92.7%). Early mortality occurred in 7 patients. Late death occurred in 322 of 1155 early survivors. The 5- and 10-year overall survival rates were 84.3% and 66.7%, respectively. Univariate analyses demonstrated that functional completeness of revascularization was a statistically significant risk factor (P = .038), whereas anatomic completeness was not (P = .859). The multivariate analysis showed that functional completeness of revascularization (hazard ratio, 1.54; 95% CI, 1.08-2.22; P = .019) and age, underweight status, diabetes mellitus, chronic kidney disease, chronic obstructive pulmonary disease, and left ventricular dysfunction were significant factors associated with long-term survival.

CONCLUSIONS

Functional rather than anatomic completeness of revascularization has a significant impact on the long-term survival in patients who undergo CABG.

External Support for Saphenous Vein Grafts in Coronary Artery Bypass Surgery: A Randomized Clinical Trial

Importance

Intimal hyperplasia and subsequent saphenous vein graft failure may have significant adverse clinical effects in patients undergoing coronary artery bypass surgery. External support of saphenous vein grafts has the potential to prevent vein graft dilation and hence slow the rate of intimal hyperplasia and increase long-term vein patency.

Objective

To determine efficacy, as measured by intimal hyperplasia, and safety of an external saphenous vein graft support device in patients undergoing a coronary bypass graft procedure.

Design, Setting, and Participants

This within-patient randomized, open-label, multicenter study was conducted at 17 Cardiothoracic Surgical Trials Network centers in North America. Between January 2018 and February 2019, 224 patients with multivessel coronary artery disease undergoing isolated bypass surgery were enrolled. For each patient, 1 of 2 vein grafts was randomized to receive external support or no support.

Interventions

External vein graft support or no support.

Main Outcomes and Measures

The primary efficacy end point was intimal hyperplasia area assessed by intravascular ultrasound at 12 months postrandomization for each study graft. Secondary confirmatory end points were lumen diameter uniformity assessed by angiography and graft failure (≥50% stenosis) by quantitative coronary angiography. Major cardiac and cerebrovascular events were collected through month 12.

Results

Among 224 patients (mean [SD] age, 65.8 [8.3] years; 178 [79.5%] male), 203 (90.6%) were eligible for intravascular ultrasound, of which 85 (41.9%) had at least 1 study graft occluded or severely diseased at 12 months (55 supported, 56 unsupported). After imputation of data missing because of graft occlusion or severe disease, the estimated mean (SE) intimal hyperplasia area was 5.11 (0.16) mm2 in supported grafts and 5.79 (0.20) mm2 in unsupported grafts (P = .07). In a sensitivity analysis of 113 patients with both grafts imaged, the mean intimal hyperplasia area was 4.58 (0.18) mm2 and 5.12 (0.23) mm2 in supported and unsupported grafts, respectively (P = .04). By 12 months, 5 patients (2.2%) died and 16 patients (7.1%) experienced a major cardiac or cerebrovascular event.

Conclusions and Relevance

The 12-month difference in intimal hyperplasia area between supported and unsupported grafts did not achieve statistical significance. Cumulative mortality and major cardiac or cerebrovascular events rates were similar to those in other randomized coronary artery bypass trials. Further investigation to assess the effect of external graft support devices on long-term graft patency and clinical outcomes is warranted.

Trial Registration

ClinicalTrials.gov Identifier: NCT03209609.

Rationale and design of a randomized trial evaluating an external support device for saphenous vein coronary grafts

BACKGROUND

Coronary artery bypass grafting (CABG) is the most common revascularization approach for the treatment of multi-vessel coronary artery disease. While the internal mammary artery is nearly universally used to bypass the left anterior descending coronary artery, autologous saphenous vein grafts (SVGs) are still the most frequently used conduits to grafts the remaining coronary artery targets. Long-term failure of these grafts, however, continues to limit the benefits of surgery.

METHODS

The Cardiothoracic Surgical Trials Network trial of the safety and effectiveness of a Venous External Support (VEST) device is a randomized, multicenter, within-patient trial comparing VEST-supported versus unsupported saphenous vein grafts in patients undergoing CABG. Key inclusion criteria are the need for CABG with a planned internal mammary artery to the left anterior descending and two or more saphenous vein grafts to other coronary arteries. The primary efficacy endpoint of the trial is SVG intimal hyperplasia (plaque + media) area assessed by intravascular ultrasound at 12 months post randomization. Occluded grafts are accounted for in the analysis of the primary endpoint. Secondary confirmatory endpoints are lumen diameter uniformity and graft failure (>50% stenosis) assessed by coronary angiography at 12 months. The safety endpoints are the occurrence of major adverse cardiac and cerebrovascular events and hospitalization within 5 years from randomization.

CONCLUSIONS

The results of the VEST trial will determine whether the VEST device can safely limit SVG intimal hyperplasia in patients undergoing CABG as treatment for coronary atherosclerotic disease.

The Use of Intraoperative Transit Time Flow Measurement for Coronary Artery Bypass Surgery: Systematic Review of the Evidence and Expert Opinion Statements

Transit time flow measurement (TTFM) allows quality control in coronary artery bypass grafting but remains largely underused, probably because of limited information and the lack of standardization. We performed a systematic review of the evidence on TTFM and other methods for quality control in coronary artery bypass grafting following PRISMA standards and elaborated expert recommendations by using a structured process. A panel of 19 experts took part in the consensus process using a 3-step modified Delphi method that consisted of 2 rounds of electronic voting and a final face-to-face virtual meeting. Eighty percent agreement was required for acceptance of the statements. A 2-level scale (strong, moderate) was used to grade the statements based on the perceived likelihood of a clinical benefit. The existing evidence supports an association between TTFM readings and graft patency and postoperative clinical outcomes, although there is high methodological heterogeneity among the published series. The evidence is more robust for arterial, rather than venous, grafts and for grafts to the left anterior descending artery. Although TTFM use increases the duration and the cost of surgery, there are no data to quantify this effect. Based on the systematic review, 10 expert statements for TTFM use in clinical practice were formulated. Six were approved at the first round of voting, 3 at the second round, and 1 at the virtual meeting. In conclusion, although TTFM use may increase the costs and duration of the procedure and requires a learning curve, its cost/benefit ratio seems largely favorable, in view of the potential clinical consequences of graft dysfunction. These consensus statements will help to standardize the use of TTFM in clinical practice and provide guidance in clinical decision-making.

Mid-Term Outcomes and Angiographic Patency of Redo Coronary Artery Bypass Grafting: A Comparison between Off-Pump and On-Pump Surgery

Background

We evaluated the mid-term outcomes and angiographic patency of redo coronary artery bypass grafting (CABG).

Methods

Of 2,851 patients who underwent isolated CABG at Seoul National University Hospital from 2000 to 2017, 88 underwent redo CABG. Patients’ mean age at redo CABG was 66.0±8.0 years. The mean interval between the first-time and redo CABG was 113.0±62.4 months. The mean follow-up duration was 86 months. Early and mid-term clinical outcomes were evaluated. Angiographic patency rates were evaluated early (1–2 days), 1 year, and 5 years after surgery. Comparative analyses between on-pump and off-pump CABG were also performed.

Results

The culprits for reoperation were previous grafts (65.6%), native coronary vessels (17.8%), and both (16.7%). Off-pump CABG was performed in 75 cases (85.2%), and the mean number of distal anastomoses was 1.8±0.8. The saphenous vein (39.7%) was used most frequently, followed by the right internal thoracic artery (28.4%), right gastroepiploic artery (21.3%), left internal thoracic artery (7.8%), and radial artery (2.8%). Operative mortality was 1.1%. The overall survival, cumulative incidence of cardiac death, and cumulative incidence of major adverse cardiac events were 71.3%,12.0%, and 23.3% at 5 years after surgery, respectively. The overall angiographic patency rates were 95.7%, 90.1%, and 92.2% on early, 1-year, and 5-year angiograms, respectively. The angiographic patency rates of saphenous vein grafts were 93.1%, 85.6%, and 91.3% on early, 1-year, and 5-year angiograms, respectively. No significant differences in clinical outcomes or angiographic patency rates were observed between the on-pump (n=13) versus off-pump (n=75) groups. Multivariable analysis revealed that age (hazard ratio [HR], 1.07; p=0.005) and chronic kidney disease (HR, 3.85; p=0.001) were risk factors for all-cause mortality.

Conclusion

Redo CABG could mostly be performed using the off-pump technique and did not show increased operative mortality and morbidities.

Endoscopic vein harvesting

Coronary artery bypass grafting is the most common cardiac surgical procedure performed worldwide and the long saphenous vein the most common conduit for this. When performed as an open vein harvest (OVH), the incision on each leg can be up to 85cm long, making it the longest incision of any routine procedure. This confers a high degree of morbidity to the procedure. Endoscopic vein harvest (EVH) methods were popularised over two decades ago, demonstrating significant benefits over OVH in terms of leg wound complications including surgical site infections. They also appeared to hasten return to usual activities and wound healing and became popular particularly in North America. Subgroup analyses of two trials designed for other purposes created a period of uncertainty between 2009–2013 while the impact of endoscopic vein harvesting on vein graft patency and major adverse cardiac events was scrutinised. Large observational studies debunked the findings of increased mortality in the short-term, allowing practitioners and governing bodies to regain some confidence in the procedure. A well designed, adequately powered, randomised controlled trial published in 2019 also definitively demonstrated that there was no increase in death, myocardial infarction or repeat revascularisation with endoscopic vein harvest. Endoscopic vein harvest is a Class IIa indication in European Association of Cardio-Thoracic Surgery (EACTS) and a Class I indication in International Society of Minimally Invasive Cardiac Surgery (ISMICS) guidelines.

Coronary Artery Bypass Grafting Transit Time Flow Measurement: Graft Patency and Clinical Outcomes

BACKGROUND

This subanalysis of the Randomized On-Off Bypass (ROOBY) trial examined transit time flow measurement (TTFM) use and its impact on graft patency and long-term clinical outcomes after coronary artery bypass graft surgery.

METHODS

Use of TTFM for ROOBY centers and surgeons was assessed. Comparative patient outcomes based on TTFM use included 1-year graft patency and 1-year and 5-year major adverse cardiac events: all-cause mortality, nonfatal myocardial infarction, and revascularization (percutaneous coronary intervention or repeat coronary artery bypass graft surgery).

RESULTS

Transit time flow measurement was used in 1067 patients (TTFM group) and not used in 501 patients (non-TTFM group); of the TTFM group, median percentage TTFM use was 79% (interquartile range, 41% to 98%) among 18 Veterans Affairs Medical Centers, and 74% (interquartile range, 13% to 98%) among 48 surgeons. Patients were comparable in age (63 ± 8.5 years TTFM vs 62 ± 8 years non-TTFM, P = .30) and estimated 30-day mortality risk (1.8 ± 1.7 TTFM vs 1.9 non-TTFM, P = .53). One-year FitzGibbon A patency was 83% (1600 of 1988 grafts) for TTFM assessed grafts and 78% (629 of 803) for non-TTFM assessed grafts (P < .01). Fewer TTFM patients had an occluded graft (29%, vs 38% non-TTFM; P = .01). Comparing TTFM patients with non-TTFM patients, 5-year major adverse cardiac event rates were 30% vs 25% (P = .06). Individual component rates were 14% vs 11% for death (P = .06), 12% vs 8.8% for myocardial infarction (P = .07), and 13% vs 12% for revascularization (P = .62).

CONCLUSIONS

The association of TTFM use with graft patency and clinical outcome is uncertain. Future randomized studies that account for patient risk factors and practice variation would help address this knowledge gap.