Major Leg Wound Complications between the Proximal and Distal Segments of Saphenous Veins Harvested by No-Touch Technique in Coronary Artery Bypass Graft Surgery: study protocol for a single-center randomized within-subject controlled clinical trial

Background : The No-Touch saphenous vein harvesting technique has been proved to reduce vein graft occlusion after coronary artery bypass graft surgery. However, the optimum segment of the saphenous vein for this technique is still undetermined. Previous studies implicated lower occlusion of proximal segments of saphenous veins compared to distal segments, but with concern of higher leg wound complications. No randomized trials have been carried out accordingly. This pilot study is a single-center randomized within-subject-controlled tria l, comparing the leg wound complications of proximal segments of saphenous veins harvested by No-Touch versus distal segments. Methods : The study is planning intending to enroll 100 coronary artery bypass graft surgery patients from our institution, with each patient requiring two vein grafts with or without cardiopulmonary bypass. Both proximal and distal segments of saphenous veins will be harvested by No-Touch technique from ipsilateral legs. The proximal vein segments will be randomized to the left or right coronary territory for bypassing. The primary endpoint is major leg wound complications at 6 days postoperatively. Secondary endpoints include major leg wound complications during 3-month follow-up and graft vessel occlusion at 3 months and 1 year. Clinical events include major adverse cardiac or cerebrovascular events and recurrence of angina Discussion : This is the �rst study assessing the safety and effectiveness between different segments of No-Touch saphenous veins for coronary artery bypass graft surgery, and will help to establish preliminary evidence for decision making of precise vein graft conduit choice.


Introduction Background and rationale {6a}
Saphenous vein grafts (SVG) are currently used in almost 80% of coronary artery bypass graft (CABG) surgery [1].The Occlusion of SVG is part of the most crucial challenges in CABG; it increases the recurrence of angina substantially, and may require repeat revascularization [2][3][4][5][6][7][8] afterwards.Less than 50% of vein grafts remain patent in 10 years after surgeries [4,9,10].The No-Touch saphenous vein harvesting technique, introduced by Dr. Souza in 1996, aimed to reduce vein graft occlusion after CABG, by preserving the integrity of SVG preferably during the harvesting [11].Short and long-term follow-up studies demonstrated less occlusion of SVG harvested by No-Touch technique compared with conventional approach [8, 12,13].Empirically, surgeons prefer to harvest veins from the distal end (shank) of the leg, which is reviewed easier to identify during harvesting.Previous studies implicated lower occlusion of proximal segments of saphenous veins compared to distal segments [8].The proximal (thigh) segment of saphenous vein is usually located deeper, resulting in a larger skin ap after surgery.
Hence, it brings to concern of leg wound complications of harvesting veins from the thigh [14].However, no studies have been performed comparing the wound complications between these two sites of vein harvesting so far.Therefore, the optimum segment of No-Touch veins for bypassing is still unde ned.

Explanation for the choice of comparators {6b}
Not applicable.

Objectives {7}
The purpose of this study is to assess, whether the safety of harvesting from proximal segment of saphenous veins by No-touch technique, is as the same as from distal segment, without increasing the incidents of leg wound complications after CABG surgery.Rates of graft occlusion between the two segments of veins for bypassing will also be compared during follow-ups.

Trial design {8}
This is a two-arm, single-center randomized within-subject-controlled trial.Patients will be randomized to bypass either the left or right coronary territory, by using their proximal segments of saphenous veins.Distal segment veins from the ipsilateral leg will be used to bypass the other coronary territory.

Study setting {9}
The study will be undertaken in the Department of Surgery, Fuwai Hospital, Chinese Academy of Medical Sciences, with an amount of isolated CABG over 4000 cases annually.Data will be collected both in hospital ward and outpatient clinic during follow-ups.A web-based and paperless data submission system (http://ccsr.cvs-china.com) for the study has been set up.All surgical procedures will be expected to complete by quali ed surgeons who have performed at least 100 CABGs.Vein harvesting will be done by quali ed senior residents.We identify senior residents who have performed at least 100 cases of vein harvesting in CABG and give them standard training of No-Touch vein harvesting.When they perform at least 50 cases of No-Touch vein harvesting, they are evaluated by two independent training surgeons to be quali ed for vein harvesting.

Surgical Procedure
Anesthetic technique and method of myocardial protection are left to individual anesthesiologists and perfusionists to decide.All patients undergo either off-pump or on-pump CABG at the surgeons' discretion on the basis of anatomic and clinical ndings.
For the No-Touch vein harvesting technique in our study, two longitudinal incisions are made on the thigh and the shank from unilateral lower limb (for harvesting of the proximal segment of saphenous vein, incision is started from about 3 or 4cms inferolateral to the pubic tubercle and then extended downward).As previously reported [11,15], the adventitia and perivascular tissues are carefully kept intact to avoid damage.Then a margin of about 5 mm from both sides of the vein is created to include the fat pedicle using electrocautery, and all visible side branches are ligated with 4-0 silk or by metal clipping (branches are divided at the pedicle margin rather than the vein trunk).The saphenous vein is then separated from its bed using scissors and the electrocautery, together with the surrounding tissue.The vein is left in situ and covered with a saline-moistened gauze until systemic heparin is administered and graft anastomosis is ready.After removal, a small adaptor is inserted into the open distal end and secured with a ligature.The pedicled vein is stored in saline solution to which heparin (2500U) and papaverine (30mg) have been added.Since heparinized blood cannot be easily obtained during off-pump CABG, we use heparinized saline with papaverine rather than heparinized blood to store vein grafts for patients undergoing either off-pump CABG or on-pump CABG.Forced distension or ushing using a syringe is strictly prohibited.
Before each anastomosis, side branches of the vein are checked by the operator and re-clipped.After proximal anastomosis is completed, each graft is re-checked for leakage due to undiscovered branches or invalid clipping and re-clipped if necessary.
Leg incisions are closed with continuous suture for both two groups.Remaining coronary bypassing techniques are according to the clinical practice of the hospital and the preference of the operators.Before chest closure, mean ow values and pulsatile index are obtained with transit-time ow measurement (Medi-stim Butter y owmeter, Medi-stim AS, Oslo, Norway).If mean ow value is less than 10 ml/min, or pulsatile index is greater than 5.0, or any possible graft kinking or compression is detected, the anastomosis is redone.
An intraoperative paper questionnaire is answered by the operator after completion of the surgery, to evaluate the quality of each vein graft.Vein quality is classi ed as good, moderate, or poor, according to whether there is varicose or aneurysmal dilatation, in ammatory wall thickness, focally thinned wall, or too-small diameter.
Although ultrasonic mapping is reported to help prevent unnecessary incision and large skin aps [8, 16], it is not commonly used in clinical practice in China.Based on our experiences, well-trained surgeons with su cient quali cations can harvest the veins with No-Touch technique without ultrasonic mapping.Ultrasonic mapping is not adopted in this study.

Criteria for discontinuing or modifying allocated interventions {11b}
Not applicable.

Strategies to improve adherence to interventions {11c}
Not applicable.
Relevant concomitant care permitted or prohibited during the trial {11d} Medication All participants are prescribed dual antiplatelet therapy with aspirin 100mg plus clopidogrel 75mg daily from the rst day post-CABG until 3 months post-operation.Prescription of other concomitant medications such as β-blockers, nitrates, statins, and antihypertensive agents, is determined by local surgeons according to ACC/AHA guidelines [17].

Primary endpoint
Major leg wound complication at 6 days postoperatively.
Major leg wound complication is de ned as a leg wound that has failed to respond to conservative treatment and required subsequent surgical interventions, such as debridement, re-suture, and delayed wound closure.Secondary endpoint 1. Major leg wound complication during 3 months after the surgery.
Graft occlusion is identi ed by MSCTA.Graft assessment is carried out according to the FitzGibbon criteria [18].Each graft is graded as A (excellent), B (fair), or O (occluded).Contrast lling of the grafts, anastomoses, and coronary arteries beyond the graft are considered in each assessment.Grade A indicates that the graft is patent with ≤50% stenosis.Grade B indicates that graft stenosis is >50% but not occluded.When a conduit does not ll with contrast at all, it is considered Grade O and included with string sign found in any segment (including proximal anastomotic site, distal anastomotic site, and main trunk).Both of these latter ndings are considered together and referred to as occlusion in the analysis.
Clinical events 1. Major adverse cardiac or cerebrovascular events (MACCE, including cardiovascular death, non-fatal myocardial infarction (MI), stroke and target vessel revascularization) at 3 months and 1 year after the CABG.
2. Individual MACCE, including cardiovascular death, non-fatal MI, stroke and target vessel revascularization at 3 months and 1 year after surgery.

Recurrence of angina
All clinical events including myocardial infarction, stroke, target lesion revascularization, and death will undergo central adjudication by an independent clinical events committee (CEC) according to prespeci ed criteria.De nition of clinical events used in adjudication is shown in Additional le 2

Participant Timeline {13}
Participant time line is shown in Fig. 1, and owchart of the study is shown in Fig. 2 Sample size {14} As a pilot trial, the primary consideration for the sample size is the ability to inform the feasibility of a fullscale study.We propose a sample size of 100 vein grafts in each group with a total of 100 patients.

Assignment Of Interventions: Allocation Sequence generation {16a}
A web-based central randomization system incorporated in the registration system is used for allocation (http://ccsr.cvs-china.com/).The randomization code with xed block size is generated by SAS.

Implementation {16c}
Enrollment of participants are performed by investigators.Each patient will be in an individual discussion with an investigator.The nature of the study and the procedure to be conducted will be explained in a way that is not di cult to comprehend.When an eligible patient signs informed consent, the investigator logs in to the randomization webpage, and obtains the random number along with the proximal group (left or right coronary territory), automatically distributed by the system after the basic patient information was con rmed.The statistician who is responsible for the randomization code and the staff that develops the Interactive Web-based Response (IWR) system, are independent of each other.

Assignment Of Interventions: Blinding
Who will be blinded {17a} Due to the nature of this surgery-based study, the investigators, CABG operators and vein harvesting surgeons will not be blinded.Participants will be blinded about which coronary territory his or her proximal vein segment is bypassed to during post-operative assessment and follow-up visit.Radiologists in charge of graft occlusion determining will also be blinded to the randomized allocation of each vein graft.

Procedure for unblinding if needed {17b}
Not applicable.

Data Collection And Management
Plans for assessment and collection of outcomes {18a} A summary of the follow-up is shown in Table 1 A postoperative questionnaire regarding leg wound condition is lled before patient discharge and during follow-up visit.Visual Analogue Scale [19] is used for evaluation of leg pain, and other wound healing disturbances including surgical debridement or re-suture, hematoma, persistent exudation, numbness of the skin, and leg edema were recorded.The Questionnaire and de nitions are presented in Additional le 3.
We  2.The investigators and study coordinators will keep in close touch with all the participants by establishing a Wechat group chat, which is the most popular mobile social software in China.

Data management {19}
A web-based and paperless data submission system (http://ccsr.cvs-china.com) for the study has been set up.For web-data transmission, a high-level secure socket layer is adopted.For in-hospital data collection, 12 modules have been set (preoperative saphenous vein screening, patient basic information, preoperative risk factors, cardiovascular presentation, tests and examinations, general information of operation, record of CABG, post-operative complications, preoperative medications, medication prescriptions at discharge, 3-month follow-up results and 12-month follow-up results) with over 300 items.Double-entry of data is required by designated study coordinators.All web-based records will be exported monthly for range checks of values by investigators.
Plans for collection, laboratory evaluation and storage of biological specimens for genetic or molecular analysis in this trial/future use {33} Not applicable.No biological specimens will be collected.

Statistical methods for primary and secondary outcomes {20a}
The trial data will be analyzed on an intention-to-treat basis of patients included in the groups assigned to randomization, irrespective of future management and events.Any intentional or unintentional deviation from the study protocol should be documented and explained in the data collecting system.Demographic, clinical variables, in-hospital death, postoperative complications, follow-up death, and MACCE will be summarized as means (SDs) for continuous and counts (percentages) for categorical variables.A generalized-estimate-equation model will be used to estimate treatment effects on the graft level wound complications and occlusion analysis, to account for the cluster effect of grafts from the same patient.A P value of less than 0.05 will be considered as statistically signi cant for all analyses.

Interim analyses {21b}
Interim analysis will be carried out when 50% of subjects nish their scheduled follow-up, according to the charter of the data safety monitoring board (DSMB).

Methods for analyses (e.g. subgroup {20b}
Considering leg wound may be a function of baseline characteristics.We plan to compare the odds ratio of leg wound complications based upon different risk groups, such as male vs, female, BMI<30 vs. BMI≥30, diabetic vs. nondiabetic, smoking vs non-smoking, with vs. without peripheral artery disease.We also plan to conduct subgroup analysis by comparing odds ratios of graft occlusion and different vein graft qualities.An intraoperative questionnaire (see Additional le 3) for evaluation of the graft quality is required to be answered by the operators.Graft quality is strati ed as good, moderate, or poor, according to the presence of side branch tears, in ammatory wall thickness, or signs of varicosity [22].Subgroup analysis will be performed using generalized-estimate-equation models.
Methods in analysis to handle protocol non-adherence and any statistical methods to handle missing data {20c} We consider the missing of the primary endpoint to be minimal.If any, missing data will be handled via worst observation carried forward (WOCF).
Plans to give to the full protocol, participant level-data and statistical code {31c} Not Oversight And Monitoring Composition of the coordinating centre and trial steering committee {5d} The role of the trial steering committee (TSC) is to monitor and supervise the progress of the study.Members of TSC are listed in Table 3.The TSC will meet prior to the start of the trial and then once every two weeks.Composition of the data monitoring committee, its role and reporting structure An independent data safety monitoring board (DSMB) is established before the start of recruitment.
There is no pre-speci ed stopping rule for the primary e cacy endpoint, so there is no need to adjust the type I error rate.The DSMB members will suggest whether the study should be stopped due to unexpected risk of patients.If the safety signal is acceptable, the study will continue to the planned recruitment number and data analysis will be built on the entire population.Members of DSMB are listed in Table 4 The optimum segment of saphenous vein graft in CABG about concerning the safety and e cacy by No-Touch technique is undetermined.Previous studies showed that the incidence of leg wound complications after CABG by open harvesting technique was from 3-25% [23].According to our database, major leg wound complications (de ned by leg that had failed to respond to conservative treatment and required subsequent surgical interventions such as debridement and resuture) after No-Touch vein harvesting was 6.2%, which was relatively low in literature ndings.However, none of these results discriminated against wound complications between proximal and distal segments of the lower limb.Therefore, the choice of site for saphenous vein conduits harvesting was based individual experience rather than evidence from researches.
The No-Touch saphenous vein harvesting technique has been proved to reduce vein graft occlusion after CABG [8, 12,13,24].However, no studies were conducted to discriminate effects on different segments of veins harvested by this novel technique.This is the rst study comparing the incidence of leg wound complications as well as SVG occlusion between proximal and distal segments of saphenous veins harvested by No-Touch technique.
Graft occlusion will be assessed as secondary endpoints in our study.Differing from previous studies, CT angiography will be used in our trial for occlusion assessment instead of coronary angiography.The decision of using of CTA during follow-ups was made in light of patient compliance, as interventional coronary angiography is much more traumatic and costly, and too many cases of refusal or loss of contact from the patients will greatly bias the result.
One limitation of this study is the small sample size.As a pilot trial, the primary consideration for the sample size is the ability to notify the feasibility of a full-scale study.The comparison of a total of 200 vein grafts will help to establish preliminary evidence for the raised questions.Another limitation is that ultrasound mapping is not adopted, which is reported to be helpful in preventing unnecessary incision and large skin aps [8,16].However, it is not commonly used in clinical practice in China and according to our experience, well-trained surgeons with su cient quali cations can harvest veins with the No-Touch technique without this instrument.
This pilot study will serve to establish preliminary evidence for the decision making of precise vein graft conduit choice.Inherently, this surgical-based clinical trial is confronted with a number of challenges, that investigators must consider when designing the trial protocol.Although the follow-up of 1-year is not very long, we may consider follow-up studies with extended follow-ups of up to 10 years.Larger scale clinical trials are being warranted in the future.

Trial Status
Enrollment of patients is planned to start from March 1st, 2020.Completion of recruitment is expected by late June, 2020 with results of the primary endpoint becoming available in August, 2020.
participate in the design and will not participate in the implementation of the study, including the collection, management, analysis, interpretation of the data and the preparation of the manuscript.
Funding documentation can be found in Additional File 6.
aged 18 or older who undergo primary isolated open-chest CABG with two vein grafts, one to the left coronary territory and the other to the right, with or without cardiopulmonary bypass.Exclusion criteria Concomitant cardiac or vascular surgeries (i.e.valve repair or replacement, Maze surgery) Redo CABG Emergent CABG (cardiogenic shock, inotropic pressure support, IABP) Severe vein varicosity as assessed after vein harvesting and before randomization Use of vascular stapler for anastomosis Endarterectomy of coronary artery during surgery Left ventricular repair due to ventricular aneurysm Concomitant life-threatening disease likely to limit life expectancy to less than two years Severe renal insu ciency (i.e.creatinine >200 μmol/L) Contraindications for dual antiplatelet therapy, such as active gastroduodenal ulcer Participant of other ongoing clinical trials Plans to promote participant retention and complete follow-up and are routine practice of the hospital.The study does not prescribe extra costs of patients.

Figure 1 Participant
Figure 1 [20,21] relevant anatomical characteristics, e.g., sites of proximal and distal anastomosis, graft type and quality, proximal lesion stenosis rate, graft ow and pulsation index, application of sequential anastomosis.As to sequential anastomosis, one failure of distal anastomosis will be considered occlusion of the sequential graft.Coordinators and investigators are required to submit complete inhospital data within 14 days of discharge.The study adheres to a rigorous standard for medical record transmission and data abstraction, similar to the previously published China Patient-Centered Evaluative Assessment of Cardiac Events (China PEACE)-Retrospective Acute Myocardial Infarction Study and the Percutaneous Coronary Intervention Study[20,21].Clinic visits are required.Study coordinators will telephone participants to recall the scheduled date of return to the hospital.The 100 randomized patients will undergo prede ned clinical follow-ups at 3 months and 12 months post-procedure.Two designated attending surgeons will inspect patients' leg wound healing at 3-month visit.MSCTA is to be performed, and image discs will be assessed by a central Core Laboratory.The results of MSCTA are independently reviewed by 2 radiologists blinded to patients' randomized allocation.Discrepancies in occlusion judgement are reviewed by a third radiologist and resolved by consensus.At each follow-up visit, all current medications and events since the last visit are recorded and compared between the two groups.A full list of classi cations of data content can be seen in Additional le 4.