A novel composite coronary bypass graft strategy: the saphenous vein bridge--a pilot study

Anterolateral territory coronary artery bypass grafting strategies: a non-inferiority randomized clinical trial: the AMI-PONT trial

OBJECTIVES

The main objective was to assess whether a composite coronary artery bypass grafting strategy including a saphenous vein graft bridge to distribute left internal mammary artery outflow provides non-inferior patency rates compared to conventional grafting surgery with separated left internal mammary artery to left anterior descending coronary graft and aorto-coronary saphenous vein grafts to other anterolateral targets.

METHODS

All patients underwent isolated grafting surgery with cardiopulmonary bypass and received ≥2 grafts/patients on the anterolateral territory. The graft patency (i.e. non-occluded) was assessed using multislice spiral computed tomography at 1 year.

RESULTS

From 2012 to 2021, 208 patients were randomized to a bridge (n = 105) or conventional grafting strategy (n = 103). Patient characteristics were comparable between groups. The anterolateral graft patency was non-inferior in the composite bridge compared to conventional grafting strategy at 1 year [risk difference 0.7% (90% confidence interval -4.8 to 6.2%)]. The graft patency to the left anterior descending coronary was no different between groups (P = 0.175). Intraoperatively, the bridge group required shorter vein length for anterolateral targets (P < 0.001) and exhibited greater Doppler flow in the mammary artery pedicle (P = 0.004). The composite outcome of death, myocardial infarction or target vessel reintervention at 30 days was no different (P = 0.164).

CONCLUSIONS

Anterolateral graft patency of the composite bridge grafting strategy is non-inferior to the conventional grafting strategy at 1 year. This novel grafting strategy is safe, efficient, associated with several advantages including better mammary artery flow and shorter vein requirement, and could be a valuable alternative to conventional grafting strategies. Ten-year clinical follow-up is underway.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01585285.

Outcomes of left internal mammary artery with saphenous vein composite graft to bypass the left anterior descending artery: a propensity-matched study

Background

This study aimed to evaluate the early and mid-term outcomes of a novel strategy of using the in-situ left internal mammary artery (LIMA) with the great saphenous vein graft (SVG) to bypass the left anterior descending artery (LAD) in coronary artery bypass grafting (CABG).

Methods

A total of 979 patients took part in this retrospective observational study; 83 patients were propensity-score matched to the LIMA + SVG group and 83 to the LIMA − LAD group. Early mortality, postoperative complications, mid-term major adverse cardiovascular and cerebrovascular events (MACCE) were compared among the two matched groups after the procedure.

Results

No significant differences in early mortality and postoperative complications rates were detected between the two matched groups. For mid-term outcomes, the incidence of MACCE was slightly higher in the LIMA + SVG group, but there was no significant statistical difference (14.9% vs. 12.8%, hazard ratio =1.20, 95% CI, 0.24 to 7.95; P=0.70) between the matched groups. Computed tomography coronary artery angiography (CTCA) images showed a LIMA + SVG composite graft patency rate of 94% (32/34) 25 months after the procedure.

Conclusions

Using the in situ LIMA with SVG to revascularize LAD was associated with comparable early and mid-term outcomes. These findings may provide an alternative emergency strategy when in situ LIMA cannot bypass LAD. Further study needs to be conducted to test longer-term outcomes.

Intraoperative Analysis of Flow Dynamics in Arteriovenous Composite Y Grafts

Objective

Composite graft of left internal thoracic artery and great saphenous vein in revascularization of the left coronary system is a technique well described in literature. The aim of this study is to analyze blood flow dynamics in this configuration of composite graft especially in what concerns left internal thoracic artery's adaptability and influence of great saphenous vein segment on left internal thoracic artery's flow.

Methods

Revascularization of left coronary system with composite graft, with left internal thoracic artery revascularizing the anterior interventricular artery and a great saphenous vein segment, anastomosed to the left internal thoracic artery, revascularizing another branch of the left coronary system, was performed in 23 patients. Blood flow was evaluated by transit time flowmetry in all segments of the composite graft (left internal thoracic artery proximal segment, left internal thoracic artery distal segment and great saphenous vein segment). Measures were performed in baseline condition and after dobutamine-induced stress, without and with non-traumatic temporary clamping of the distal segments of the composite graft.

Results

Pharmacological stress resulted in increase of blood flow values in the analyzed segments (P<0.05). Non-traumatic temporary clamping of great saphenous vein segment did not result in statistically significant changes in the flow of left internal thoracic artery distal segment, both in baseline condition and under pharmacological stress. Similarly, non-traumatic temporary clamping of left internal thoracic artery distal segment did not result in statistically significant changes in great saphenous vein segment flow.

Conclusion

Composite grafts with left internal thoracic artery and great saphenous vein for revascularization of left coronary system, resulted in blood flow dynamics with physiological adaptability, both at rest and after pharmacological stress, according to demand. Presence of great saphenous vein segment did not alter physiological blood flow dynamics in distal segment of left internal thoracic artery.

A morphometric 3D model of coronary artery bypass graft dysfunction with multidetector computed tomography

OBJECTIVE

The objective was to assess, with computed tomography (CT) angiography, quantitative morphological parameters of a composite coronary artery bypass grafting (CABG) strategy and to correlate these with graft dysfunction.

FINDINGS

Forty patients [median postoperative time, 32 (14-51) months] underwent CT angiography. Graft patency was assessed, and specific quantitative morphological parameters of the graft were collected. Graft segments had an overall patency rate of 93% (78/84). Two specific morphological parameters were found to be associated with graft dysfunction.

CONCLUSION

A CT morphometric model can be used to identify quantitative 3D parameters associated with graft dysfunction. Such an approach could help in developing and improving CABG designs.

Intra-operative Graft Blood Flow Measurements for Composite and Sequential Coronary Artery Bypass Grafting

Objectives

Intraoperative assessment of coronary artery bypass grafts (CABG) anastomotic quality can be performed using transit-time flowmetry (TTF). The aim of this study was to compare on- versus off-pump coronary graft TTF and early postoperative outcomes.

Materials and methods

Between January 2009 and January 2010, 521 distal graft flows were assessed using TTF measurements in 253 consecutive patients undergoing primary isolated CABG surgery. Data were analyzed using multilevel models accounting for clustering among surgeons and grafts performed in the same patient.

Results

Mean age was 66 ± 10 years and 22% were female (n = 55) with 34% diabetics (n = 86) and 40% pre-operative myocardial infarction (MI) (n = 101). The surgeries were performed off-pump in 67% (n = 170) with sequential vein grafts in 57% (n = 144) of patients. Off-pump patients had higher pre-operative left ventricular ejection fractions (LVEF), fewer urgent surgeries, fewer distal anastomoses, and fewer sequential vein grafts (all p<0.001). Intra-operative coronary graft TTF measurements were lower in sequential vein grafts performed off-pump versus on-pump. More patients in the on-pump group needed milrinone or dobutamine 24-48 h postoperatively (p = 0.005). Independent predictors of lower TTF included female gender and off-pump surgery, whereas predictors of better TTF were pre-operative MI, larger coronary diameter at the site of the distal anastomosis, and sequential vein grafting.

Conclusions

Lower intra-operative TTF measurements were found in sequential vein grafts in offpump CABG. However, off-pump patients experienced similar short-term outcomes compared to on-pump patients.

256-slice CT angiographic evaluation of coronary artery bypass grafts: effect of heart rate, heart rate variability and Z-axis location on image quality

Purpose

The objective of this study is to assess the effect of heart rate, heart rate variability and z-axis location on coronary artery bypass graft (CABG) image quality using a 256-slice computed tomography (CT) scanner.

Methods

A total of 78 patients with 254 CABG (762 graft segments) were recruited to undergo CABG assessment with 256-slice CT and prospective ECG-gating. Two observers rated graft segments for image quality on a 5-point scale. Quantitative measurements were also made. Logistic and cumulative link mixed models were used to assess the predictors of graft image quality.

Results

Graft image quality was judged as diagnostic (scores 5 (excellent), 4 (good) and 3 (moderate)) in 96.6% of the 762 segments. Interobserver agreement was excellent (kappa ≥0.90). Graft image quality was not affected by heart rate level. However, high heart rate variability was associated with an important and significant image quality deterioration (odds ratio 4.31; p  =  0.036). Distal graft segments had significantly lower image quality scores than proximal segments (p ≤ 0.02). Significantly higher noise was noted at the origin of the mammary grafts (p  =  0.001), owing to streak artifacts from the shoulders.

Conclusion

CABG imaging with 270-msec rotation 256-slice CT and prospective ECG-gating showed an adequate image quality in 96.6% of graft segments, and an excellent interobserver agreement. Graft image quality was not influenced by heart rate level. Image quality scores were however significantly decreased in patients with high heart rate variability, as well as in distal graft segments, which are closer to the heart.

Composite versus conventional coronary artery bypass grafting strategy for the anterolateral territory: study protocol for a randomized controlled trial

Background

In severe coronary artery disease, coronary artery bypass grafting (CABG) surgery is indicated to re-establish an adequate blood supply to the ischemic myocardium. Effectiveness of CABG surgery for symptom relief and mortality decrease should therefore depend on bypass graft patency. As bypass using a left internal mammary artery (LIMA)-to-left anterior descending coronary artery (LAD) anastomosis allows the best results in terms of graft patency, we designed a new surgical technique using a saphenous vein graft as a venous bridge to distribute the LIMA flow to the cardiac anterolateral territory. This novel strategy could extend the patency benefits associated to the LIMA. Other potential benefits of this technique include easier surgical technique, possibility to use saphenous vein grafts as vein patch angioplasty, shorter saphenous vein grafts requirement and reduced or eliminated manipulations of the ascendant aorta (and associated stroke risk).

Methods/Design

Between July 2012 and 2016, 200 patients undergoing a primary isolated CABG surgery using cardiopulmonary bypass with a LAD bypass graft and at least another target on the anterolateral territory will be randomized (1:1) according to 1) the new composite strategy and 2) the conventional strategy with a LIMA-to-LAD anastomosis and revascularization of the other anterolateral target(s) with a separated aorto-coronary saphenous vein graft. The primary objective of the trial is to assess whether the composite strategy allows non-inferior anterolateral graft patency index (proportion of non-occluded CABGs out of the total number of CABGs) compared to the conventional technique. The primary outcome is the anterolateral graft patency index, evaluated at one year by 256-slice computed tomography angiography. Ten years of clinical follow-up is planned to assess clinical outcomes including death, myocardial infarction and need for revascularization.

Discussion

This non-inferiority trial has the potential to advance the adult cardiac surgery field, given the potential benefits associated with the composite grafting strategy.

Trial registration

ClinicalTrials.gov: NCT01585285.