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Interact CardioVasc Thorac Surg 2008;7:789-793. doi:10.1510/icvts.2008.183665 © 2008 European Association of Cardio-Thoracic Surgery
Off-pump coronary artery bypass surgery in very high-risk patients: adjustment and preliminary results
a Department of Cardiac Surgery and Anesthesiology, Hôpital Cardiologique du Haut-Levêque, 33600 Pessac, France Received 13 May 2008; received in revised form 24 June 2008; accepted 30 June 2008
*Corresponding author. Cardiovascular Surgery Department, Haut-Lévêque Hospital, Avenue de Magellan, 33600 Pessac, France. Tel.: +33 5 57 65 65 65; fax: +33 5 57 65 34 31.
Left ventricle dysfunction and comorbidities are responsible for a large number of complications after CABG. OPCAB could be an interesting alternative for very high-risk patients. Patients were included if EuroSCORE >9, or with at least two of the following criteria, severe LV dysfunction, recent myocardial infarction (MI), terminal renal failure, lung dysfunction, PVD, BMI>30. Patients were operated using the Octopus® (Medtronic) system. One hundred and twenty patients, mean age 68±10 years, 72% male, were operated. Mean EuroSCORE was 10.2±5.3, LV function 36.79±11.3%, recent MI 57%, renal failure 52%, COPD 44%, PVD 52%, obesity 34%. Mean graft per patient was 2.1±0.8. Three patients underwent secondary PTCA treatment for incomplete revascularization. Combined surgery was required for 20%. Early mortality was 3%. Intensive care unit stay was 2.7 days. Early complications were: low output syndrome 3%, MI 0.8%, stroke 0.8%, kidney support 7%. Graft patency was systematically analyzed with MCTA or angiocardiography. OPCAB strategy seems to be safe and secure in this population of very high-risk patients reducing multi-organ failure. However, long-term results are needed to confirm this strategy.
Key Words: Coronary artery bypass graft; Off-pump; High-risk surgery
CABG still remains the benchmark treatment today for patients with three-vessel disease. The indications are well documented and the results relatively satisfying in terms of morbidity/mortality and ischemic resurgence [1]. The incidence of risk factors and preoperative comorbidities is increasing [2] and many patients arrive for surgery at an advanced age, with severe left ventricular dysfunction, chronic renal disease, peripheral vascular disease, chronic bronchopulmonary disease, etc. To improve the management of these patients, surgeons have had to adapt their operating techniques. CPB can trigger numerous complications or worsen pre-existing organ damage (cardiac, pulmonary, renal), which in turn may increase operative morbidity/mortality. OPCAB strategy is to be able to carry out revascularization as complete as possible, under technical conditions offering maximum safety for the patient, by avoiding triggering of possible complications induced by CPB and by avoiding myocardial ischemia [3, 4]. It seems that OPCAB offers results at least equal compared to CPB under cardiac arrest in terms of low or moderate surgical risk patient [5]. However, few studies published in the literature point out the interest of this strategy for very high-risk patients, who have severe and multiple comorbidities [6]. In our department, we have tried to develop optimized management of patients requiring coronary bypasses and who present severe comorbidities. The aim of the present study was to assess the early results of coronary revascularization using the OPCAB technique in patients presenting a very high surgical risk.
2.1. Construction of study and population This was a prospective, single center, single surgeon (LB) study. The indications for CABG were established according to AHA/ESC guidelines [1]. Myocardial ischemia was systematically checked with scintigraphy before the surgery to point the area to revascularize. The criteria defining very high surgical risk was a EuroSCORE >9. Other criteria were as follows: age over 75 years, BMI >30, severe left ventricular dysfunction <30%, PVD with Ankle Brachial Index <0.9, severe chronic renal disease with clearance <40 ml/min, acute or recent MI (<90 days), severe chronic obstructive pulmonary disease (COPD) proved by functional respiratory testing. The combination of at least two of the above criteria meant that these patients were eligible for OPCAB. Each patient had a monitoring of blood pressure, a Swan-Ganz catheter, and transesophageal echocardiography. A cell saver was used systematically. Grafts were taken from the LIMA, the RIMA and the great saphenous vein. Peroperative heparin therapy was 300 U/kg with ACT maintained at >450 s. All patients were operated by median sternotomy except for three by left lateral thoracotomy (bypass redo with a permeable LIMA on LAD). Myocardial stabilization was ensured by using the OCTOPUS® (Medtronic) stabilizer readily combined with STAR FISH (Medtronic) apical suction. In some cases, particularly with LV enlargement, the surgery was technically difficult: the assistance of starfish suction, the left pleural cavity opening and the mobilization of operating table offer the possibility of carrying out the procedure under safe conditions. Distal anastomoses were carried out first of all with the assistance of coronary constrictors or shunts if constriction was not well tolerated at the rhythmic and hemodynamic level. Each graft was monitored by Doppler ultrasound and importance was given to diastolic flow and to the ratios of velocity index. In the presence of any doubt we undertook immediately the distal anastomosis with the same technique. Concerning mitral valve insufficiency, a grade more than two with severe LV <25% was not corrected, and a Corcap device was indicated to shape the LV geometry. If the EF was more than 30%, the surgery was performed on pump with MV correction. 2.3. Data collection and organization of follow-up In the ICU, the elements collected were the following: average length of stay, time to extubation, bleeding transfusion, revision, low output cardiac syndrome, cardiac rhythm disorders, the need to prescribe diuretics, vasopresssive amines, cardiotonic agents, aortic counterpulsation balloon, reintubation. Bioassays included cardiac enzymes (troponin Ic, CPK-MB), creatinine, as well as the usual resuscitation elements. The definition of a peroperative infarct was based on a new Q wave on the ECG and/or a troponin Ic rate of >2.5 ng/ml, and/or a CPK-MB rate of >100 ng/ml. All significant elements or morbid complications, both during hospital stay and during rehabilitation, were then listed.Each patient had a systematic multidetector computed tomography angiography (MCTA) to ensure graft patency. The first 50 patients underwent a systematic coronarography. The adequation with the results of the MCTA meant that we retained the indication for coronarography only if there was any doubt as to graft patency on the MCTA and/or in the case of secondary procedure for hybrid revascularization.
3.1. Population characteristics From January 2005 to January 2008, 127 patients were eligible for our study. Two died before their procedure and three did not want to undergo OPCAB. One hundred and twenty patients were therefore finally included in the present study. The preoperative characteristics of the patients are detailed in Table 1.
3.2. Peroperative data The peroperative data can be found in Tables 2 and 3. Average rate of bypass per patient was 2.1±0.8. Revascularization was considered complete in approximately 90% of cases. In three cases, the circumflex artery was too small to be grafted. Two patients were dilated from the left main and one from a posterolateral after single LAD bypass. This hybrid strategy was decided prior to the procedure. Four patients presented an intramyocardial LAD but we did not observe non-feasible anastomosis. In all, 7% of patients were considered to have incomplete revascularization. There were no peroperative conversions to CPB, but 3% of patients arrived in the operating room under ECMO for post-infarction cardiogenic shock. The bypasses were then carried out without aortic clamping under peripheral circulatory support. An additional surgical procedure was carried out in 20% of cases (Table 3). Thirty-one percent of patients operated with a single LAD bypass benefited either from a Corcap® ventricular support device or peroperative epicardial biventricular resynchronization. Three patients were operated by left posterolateral thoracotomy for redo with patent LIMA on LAD. All received a bypass between the descending thoracic aorta and the posterolateral coronary artery using the great saphenous vein.
3.3. Immediate postoperative data Postoperative data are detailed in Table 4. Immediate postoperative mortality (day 30) was 3%. Two patients died from low postoperative cardiac output syndrome and one from digestive hemorrhage after rupture of esophageal varices.
Myocardial complications: Low output cardiac syndrome with necessity of cardiotonic agents and IAB was required by 3% of patients. Respiratory complications: Seven percent of patients required reintubation, either for cardiogenic shock, or for respiratory infection, or for bronchial congestion. Hemorrhagic complications: Mean postoperative bleeding was 722±311 ml for the first 24 h. Five percent of patients had a chest revision due to significant postoperative bleeding and more than 54% of patients required transfusion. Renal complications: Forty percent of patients presented postoperative oliguria (urinary output <0.5 ml/kg) and required intravenous diuretics. Ten percent of patients saw their preoperative renal function deteriorate temporarily and 7% required treating with continuous hemofiltration for several days. All the hemofiltrated patients presented a preoperative creatinine rate of >300 µmol/l. All surviving patients underwent a MCTA (Fig. 1) to demonstrate graft patency. One bypass using the great saphenous vein to the posterolateral was more than 70% stenosed due to excessive length. It was successfully treated with angioplasty and stent. Two other bypasses destined to the posterolateral were thrombosed. No additional treatment was effected.
Comorbidities and preoperative organ defects are more and more frequent [2], and the surgical prognosis is therefore poor. New surgical concepts have been developed to carry out optimum surgical revascularization, while decreasing the incidence of decompensation due to underlying defects and reducing the consequences induced by CPB and myocardial ischemia [3]. OPCAB has enabled improvement in morbidity and mortality for our patients and the results seem to be even more conclusive in high-risk patients [7]. The purpose of the present study was to assess early results of OPCAB strategy in patients presenting a very high surgical risk, with a wide combination of comorbidities. When patients were eligible to take part in our study, and if their clinical state permitted, each benefited from maximum optimization of their preoperative defects [2]. Preoperative analysis of our population confirmed the relatively severe state of all our patients. Approximately 46% of the patients presented a logistic EuroSCORE higher than 20% and 59% had an additive EuroSCORE higher than 9. Our operative mortality rate remains reasonable and these results have already been found by other teams working in slightly less difficult terrain [8]. All the results pertaining to this strategy seem conclusive both in postoperative mortality and in morbidity [8], given that the definition of inclusion criteria was based only on a EuroSCORE  5, and severe associated comorbidities in only 10% of cases. Three percent of patients presented cardiac decompensation through low output syndrome, given that 57% presented a recent MI, and more than 30% acute pulmonary edema in the month preceding the surgical procedure. In addition, more than 40% of patients presented severe left ventricular dysfunction (under 30%). The results of postoperative protection of left ventricular dysfunction have been found both in elective surgery and in acute phase of myocardial infarction [9]. However, after analyzing our preliminary results, we now believe that using mechanical assist devices would be an interesting alternative in patients needing CABG with cardiogenic shock. This strategy would overcome the low cardiac output syndrome during the procedure, probably reducing the consequences of multi-organ malperfusion. In our population we found severe comorbidities: 50% had a relatively high preoperative renal disease, one out of two patients presented significant PVD and around 31% of patients presented carotid stenosis of more than 50%. The incidence of COPD was also high (44%) and the total number of complications induced was relatively small in our study [10–12]. As demonstrated in other studies, we did not find this saving in blood transfusions nor the reduction in postoperative pericardial revision, probably because of the high incidence of patients under bi-antiaggregating agents and under anticoagulants, as well as the high frequency of patients presenting comorbidities affecting coagulation. We think that the failure in less postoperative bleeding and blood transfusion was dependant on this situation [12]. Our rate of bypasses per patient was not high (2.1 bypasses/patient) and revascularization was considered to be complete in 90% of cases. The anterior wall was systematically revascularized with the exception of three patients in which we performed a lateral revascularization for a redo surgery. Severe left ventricular dysfunction in certain patients meant that we prescribed either a ventricular contention combined with a Corcap® cardiac support device [13], or peroperative biventricular resynchronization [14]. In addition, the severe condition of certain patients meant that we prescribed preoperative hybrid revascularization, combined with isolated anterior wall revascularization, as has already been described by other teams [15]. We did not compare before and after the surgery the EF and myocardial perfusion due to the fact that cardiac evaluation was carried out too early. It would be interesting to do that later to show an eventual improvement in tissue perfusion. Our study shows that the strategy of not using CPB in these very high surgical risk patients seems to be feasible and safe with acceptable induced complications. However, the severe condition of these patients sometimes dictates a type of surgery where revascularization is aimed more at target vessels than on the idea of full and complete revascularization. The evaluation of residual ischemia should be systematically checked at three months and it would be possible to increase the hybrid rate strategy to improve the revascularization. In conclusion, we now need to analyze our long-term results to find out if our strategy remains beneficial for this type of patient. We currently organize a double blinded randomized study comparing in very high-risk patients CBP under cardiac arrest vs. OPCAB strategy.
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Abstract
1. Introduction