Graft patency study in off-pump coronary artery bypass surgery
Arani Raghavendra Rao Raghuram, Krishnaswamy Subramanyan, Subbiah Sivakumaran, Purushothaman Chandrasekar, Subramanian Harikrishnan, et al. Indian Journal of Thoracic and Cardiovascular Surgery ISSN 0970-9134 Volume 34 Number 1 Indian J Thorac Cardiovasc Surg (2018) 34:6-10 DOI 10.1007/s12055-017-0587-x
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Author's personal copy Indian J Thorac Cardiovasc Surg (January–March 2018) 34(1):6–10 DOI 10.1007/s12055-017-0587-x
ORIGINAL ARTICLE
Graft patency study in off-pump coronary artery bypass surgery Arani Raghavendra Rao Raghuram 1,2 & Krishnaswamy Subramanyan 1 & Subbiah Sivakumaran 1 & Purushothaman Chandrasekar 1 & Subramanian Harikrishnan 1 & Govindarajan Arunkumar 1
Received: 19 June 2017 / Revised: 9 August 2017 / Accepted: 14 August 2017 / Published online: 29 August 2017 # Indian Association of Cardiovascular-Thoracic Surgeons 2017
Abstract Purpose Off-pump coronary artery bypass (OPCAB) is known to reduce operative morbidity, intensive care and hospital stay and blood usage. Recent reports have highlighted the poor results after off-pump coronary artery bypass. So, we decided to look at the angiographic patency of our patients at the end of 3 months. Methods Out of 265 patients who underwent isolated primary coronary artery bypass graft surgery (CABG) in a 2-year period at our institution, 118 are the subjects for this study. The anticoagulation and antiplatelet protocols are explained in detail. These patients underwent computerised tomography (CT) of coronary arteries to evaluate the graft patency. The results were studied by a competent radiologist with advanced Windows 4.7 workstation. Results There were 118 patients with a total of 380 anastomoses for evaluation. Twenty patients (16.95%) had some of their grafts blocked. Out of a total of 380 anastomoses, 24 were found to be blocked (6.3%). Left internal mammary artery had 98.3% patency. Left radial artery showed a patency rate of 96%. Saphenous vein grafts had a patency rate of 91.2%. The anterior and inferior territory grafts were patent in greater than 95% of patients, whereas lateral wall grafts were patent in 86% of patients. There was no mortality in this series. One patient reported angina. Fifty-eight patients had a treadmill
* Arani Raghavendra Rao Raghuram
[email protected]
1
Institute of Cardiac Sciences, SRM Institutes of Medical Sciences (SIMS), 1, Jawaharlal Nehru Road, Vadapalani, Chennai 600026, India
2
3A, Parijath, 16 Coats Road, T Nagar, Chennai 600017, India
test and 51 were negative and 7 had positive results for inducible ischemia. Conclusions OPCAB is a safe technique with acceptable clinical outcome and angiographic patency in experienced hands. Keywords Coronary artery bypass grafting . Left internal mammary artery . Radial artery
Introduction Off-pump coronary artery bypass (OPCAB) is known to reduce operative morbidity, intensive care and hospital stay and blood usage [1–4]. The proportion of OPCAB in Western countries is around 15–20% [5, 6]. In India, OPCAB is done in about 55% of patients [7]. Recent reports [10, 11] have highlighted the suboptimal results after OPCAB. So, we decided to look at the angiographic patency of our patients at the end of 3 months.
Methods Patients During the study period between May 2014 and May 2016, 265 patients underwent isolated first-time OPCAB in our institution. Of these, 118 patients from this group form the subject for this study. The others were not included in this study for various reasons like inability to come from far off places, age greater than 75 years, serum creatinine >1.6 mg%, financial limitations or unwillingness to undergo the computerised tomography (CT) angiography. There were 98 men and 20 women in this group. Informed consent was obtained from all patients before surgery. The relevant
Author's personal copy Indian J Thorac Cardiovasc Surg (January–March 2018) 34(1):6–10
preoperative details are given in (Table 1). All these patients were evaluated at the end of 3 months for left ventricular function by echocardiography, treadmill test (TMT) and CT coronary angiography (CT CAG) after obtaining informed consent. Surgical technique All patients were operated by median sternotomy after withdrawal of antiplatelet agents for 5 days prior to surgery. Left internal mammary artery (LIMA) was dissected by pedicled fashion after administering 5000 u of heparin intravenously in 117 patients. The radial artery was harvested in 22 patients by open technique. All but 10 patients had their saphenous vein harvested by open method. Ten patients had endoscopic vein harvesting. The IMA was sprayed with dilute papaverine solution after division. The radial artery and veins were immersed in 50 ml of heparinised blood mixed with 5 mg nitroglycerin and 15 mg diltiazem. Heparin was administered in a dose of 3-mg/kg body weight before grafting, and an activated clotting time (ACT) of >350 was maintained. The first graft was LIMA to left anterior descending artery (LAD). Then, the lateral wall vessels are grafted, and lastly, the right-sided grafts were done. All patients were subjected to epiaortic scanning, and those with significant aortic disease had an anaortic approach. All the others had their proximal anastomosis done during a single partial clamping. (Table 2) gives the details of the conduits used. Occasional patients who were unstable were managed by immediate perfusion after every distal anastomosis through a cannula placed in the ascending aorta (Quickflo DPS Medtronic Inc.). After all the anastomoses are over, the heparin was partially reversed with half the calculated dose of protamine. Three-hundred milligrams of aspirin and 600 mg of clopidogrel were administered 1 h after shifting to intensive care unit and excluding significant drainage. If the first hour drainage is high, it is closely monitored and antiplatelet agents are administered at the earliest. Dual-antiplatelet therapy is prescribed from day 1. No patient needed reexploration for bleeding. All patients with radial artery graft had calcium channel blocker from day 0. Statins were started from day 1. The number of grafts needed for each patient was decided before surgery, and no patient left the operating room without
7 Table 2
Conduit details
Preoperative details
Total number of patients Age in years Sex Ejection fraction Diabetes Smoking Previous MI
118 Range 32–82, median 58.5 Male 98: female 20 Median 61% 87 (73.7%) Male 49 (50%); female 0% 58 (49%)
Number of grafts
LIMA-117 (99%)
Single = 03 (2.5%)
RIMA-06 (5%)
Double = 16 (13.5%)
LRA-22 (18.6%) SVG-106 (90%)
Triple = 57 (48%) Four = 37 (31%)
Average number of grafts = 3.22
Five = 4 (3%) Six = 1 (0.8%)
LIMA left internal mammary artery, RIMA right internal mammary artery, LRA left radial artery, SVG saphenous vein graft
the specified grafting done, thus achieving an index of completeness of revascularisation (ICOR) of 100%. CT CAG All angiograms were studied by a single radiologist with special interest in this field. The study was done using 128 slice scanner using auto MA technique. Of the non-ionic contrast, 80–100 ml was administered intravenously at a rate of 4–5 ml/ s using pressure injector. Postprocessing was done using an advanced Windows 4.7 workstation. The area between diaphragm and just above the clavicle was scanned. Each graft was studied at the aortic end, entire body and distal anastomotic site specifically.
Results One patient had symptoms suggestive of angina. All the others had complete symptom relief. Treadmill test could be done in 58 patients only. Those above 70 years and patients suffering from arthritic pain and some with apprehensions in walking on the treadmill were excluded. Out of these 58 patients, 7 had treadmill positivity for inducible ischemia. There were a total of 380 distal anastomoses available for evaluation in 118 patients (Table 3). Twenty of these 118 patients had a few of their grafts blocked. In all, there were Table 3
Table 1
Graft details
Results
Total no. of patients with blocked grafts Total no. of blocked grafts LAD territory blocks Circumflex territory blocks RCA territory blocks Anginal symptoms Coronary reintervention Mortality Reexploration for bleeding
20/118 (16.9%) 24/380 (6.3%) 4/150 (97.3% patency) 17/122 (86% patency) 4/108 (96.3% patency) 1 0 0 0
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24 dysfunctional grafts amongst 380 (6.3%). Out of these, 22 were occluded and 2 were dysfunctional. These two were LIMA grafts to LAD and both these grafts were opacified but looked atretic. The corresponding LAD was found to have 60–70% stenosis, and the competitive flow was thought to be responsible for this hypoplastic segment of LIMA. Out of 117 LIMA, only these 2 patients had dysfunctional grafts. There were no occluded LIMA grafts. Out of 25 radial artery distal anastomoses, one was occluded. The radial was used to sequentially graft the first diagonal and first obtuse marginal vessel. The angiogram showed occlusion of radial artery from aortic end to diagonal origin. The segment of radial artery between diagonal and marginal was opacified. The diagonal stenosis appeared significant. So, the occlusion must be because of technical reasons at aortic end. The grafts to the LAD territory showed a high degree of patency (146/150 = 97.3% patency). In the circumflex territory, there were 122 distal anastomoses, of which 53 were sequential and the rest single anastomosis. Seventeen out of this 122 were occluded (86.1% patency). Three amongst these patients had a sequential anastomosis to two marginal. So, 6/65 of single anastomosis and 6/ 57 of sequential anastomosis were occluded. In the right coronary artery (RCA) territory, there were a total of 108 anastomoses, of which 3 were occluded (97.2% patency). All the occluded grafts were venous grafts except one radial artery graft to lateral wall sequentially anastomosed to high diagonal and first marginal artery. The only patient who was symptomatic had an occluded sequential graft to posterior descending and posterolateral branch of right coronary artery. The patency rate was 97.3% in LAD territory, 86% in circumflex territory and 97% in RCA territory.
Discussion OPCAB is known to reduce operative morbidity, intensive care and hospital stay and blood usage [1–4]. The proportion of OPCAB in Western countries is around 15–20% [5, 6]. OPCAB is the commonest method of surgical revascularisation in India. Of the CABGs, 55% are performed by OPCAB technique in India [7]. Recent reports have highlighted the poor results after OPCAB in Western studies. There is just one report of angiographic follow-up of Indian patients [8]. So, we decided to look at the angiographic patency of the grafts in our patients at the end of 3 months from the date of surgery. The 3-month time interval was decided based on our assumption that most grafts would close off by then if there are technical issues in the conduct of the operation, and this study is to look at the criticism that OPCAB provides a technically inferior quality revascularisation. PRAGUE-4 trial [9] reported from Czech Republic randomised 400 consecutive patients to on-pump and OPCAB strategy, and 255 of them were assessed for the
Indian J Thorac Cardiovasc Surg (January–March 2018) 34(1):6–10
angiographic patency at 1 year. The arterial graft patency at 1 year was 91% for both groups. The saphenous vein patency was non-significantly lower in OPCAB group (59 vs 49%). None of these patients were on dual-antiplatelet therapy following surgery. Only 41% of patients received aspirin from first postoperative day. Our vein graft patency rate of 91.2% may partly be ascribed to the early institution of antiplatelet therapy in our patients. The CORONARY trial [10] is a multicentre trial involving 79 centres from 19 countries randomising 4752 patients to undergo CABG by one of these techniques. They were studied at 30 days. There was no difference in primary outcomes which includes death, non-fatal myocardial infarction (MI) and new renal failure requiring dialysis. There was significant reduction in blood usage, acute kidney injury and respiratory complications in the OPCAB group. The rate of early repeat revascularisation was significantly higher in this group. There was no angiographic follow-up of these patients. The 5-year results are available now and there is no significant difference in various outcomes in this period of follow-up [11]. The ROOBY trial [12] from the Department of Veterans Affairs randomised 2203 patients and studied 62% of them by angiography at 1 year. OPCAB resulted in fewer patent grafts with both arterial and venous conduits (85.8 vs 91.4% for arteries and 72.7 vs 80.4% for veins p < 0.001). The 1-year non-fatal MI was 8.1% for OPCAB and 5.6% on pump. Repeat revascularisation was significantly higher in the OPCAB group (6.3 vs 3.7%). The major limitation of this study is the limited experience of the operators. OPCAB is a technique which requires considerable training and dexterity. Any surgeon with just 20-case experience cannot be expected to produce consistent results especially with lateral wall revascularisation. The proof of this is the fact that they have observed new lesions at the site of anastomosis or just distal to it in 4.3% of OPCAB group compared to 2.2% in on-pump group (p value
