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Ann Thorac Surg 2007;84:498-502
© 2007 The Society of Thoracic Surgeons
a Department of Cardiac Surgery and Cardiology, Clinique Saint Luc, Brussels, Belgium
b Cliniques Universitaires Saint Luc, Brussels, Belgium
Accepted for publication March 26, 2007.
* Address correspondence to Dr Etienne, Department of Cardiac Surgery, Clinique Saint Luc, Bouge, Brussels, 5004, Belgium (Email: pierre.yves.etienne{at}skynet.be).
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Abstract |
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Methods: We evaluated combined beating heart procedures and preoperative IABP in selected high-risk patients and compared our results with the predictive European System for Cardiac Operative Risk Evaluation (EuroSCORE) model. Fifty-five high-risk patients with a mean logistic EuroSCORE of 24 were prospectively enrolled and then divided into emergency (group 1, n = 25) and nonemergency (group 2, n = 30) groups. IABP was inserted immediately before operation in group 1 and the day before the procedure in group 2.
Results: Compared with the EuroSCORE predictive model, a dramatic decrease in mortality occurred in both groups. Group I predicted mortality was 36.8%, and observed was 20%; and group 2 predicted mortality was 15.2% and observed was 0%. No specific complications from the use of IABP were encountered. During mid-term (2 years) follow-up, no patient died from a cardiac cause or required percutaneous coronary intervention or subsequent reoperation due to incomplete revascularization.
Conclusions: The combined use of preoperative intraaortic counterpulsation and beating heart intervention allows complete revascularization in high-risk patients with a important reduction in operative mortality and excellent mid-term results.
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Introduction |
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TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
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Off-pump coronary artery bypass (OPCAB), however, is not yet considered the gold standard by most coronary surgeons. Moreover, unstable angina or low left ventricular ejection fraction (LLVEF) are frequently cited as contraindications to beating heart interventions. The intent of this study was to evaluate the effects of preoperatively inserted IABP in combination with off-pump operation in select high-risk patients with unstable angina and LLVEF and to compare our results with the predicted mortality from the European System for Cardiac Operative Risk Evaluation (EuroSCORE) [13]. The study was approved by the Institutional Review Board in March 3, 2000, and informed consent was obtained from all patients.
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Patients and Methods |
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TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
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Preoperative Management and Intraaortic Balloon Pump Insertion
Insertion criteria were defined as follows: group 1 included 25 emergency patients, of whom 12 had unstable angina with elevated ST modification, 9 had evolving infarction (including failure of percutaneous coronary artery disocclusion in 2), and 4 had cardiogenic shock. Group 2 included 30 nonemergency patients, of whom 23 had prophylactic insertion of IABP owing to a preoperative ejection fraction of less than 0.30 as assessed by left ventriculography, transesophageal echocardiography, or both. Insertion occurred in 6 elective and 17 unstable patients. The 7 remaining patients had stabilized rest angina despite 95% stenosis of the left main trunk and an occluded right coronary artery.
In group 1, the IAPB was inserted in the catheterization laboratory before or just after coronary angiography, and the patient was immediately transferred to the operating room for surgical revascularization because of persistent electrocardiographic (ECG) abnormalities or persistent hemodynamic instability. In group 2, the IABP was inserted 12 to 24 hours preoperatively for clinical, electrical, or hemodynamic stabilization and was usually removed 48 hours postoperatively [14]. The IABP was inserted percutaneously for all patients and was set at a 1:1 ratio. Heparin was systematically used for anticoagulation. IABP size moved from 9F in the beginning of our experience to 7.5F for the more recent patients.
Logistic EuroSCORE mortality was calculated for all patients and compared with observed mortality (Fig 1). Preoperative patient characteristics and risk factors are listed in Table 1. EuroSCORE patient characteristics are listed in Table 2.
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The left anterior descending artery was revascularized first in all patients. In cases of vein grafting, the proximal anastomosis of the vein on the aorta was performed before the distal anastomosis under side clamping. The IABP was placed on stand-by during the proximal anastomosis. A cell-saving device was used in all patients.
Preoperative, operative, and postoperative variables between the groups investigated included the 30-day operative mortality, neurologic events, perioperative infarction, renal insufficiency, pulmonary infections, rhythm disturbances, mediastinitis, and reoperations for excessive postoperative bleeding or ischemia.
Statistical Analysis
Results are expressed as the mean value ± standard deviation. Comparison of continuous variables was accomplished using the t test, and categoric variables were compared with the 
2 test. Statistical significance was considered at a value of p < 0.05.
Insertion of the IABP in group 2 was not considered as preoperative critical care for calculation of the predictive mortality in this subgroup of patients to avoid overestimation of the calculated mortality risk.
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Results |
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Hospital Mortality
Hospital mortality occurred in 5 patients (9.1%) on postoperative days 1, 9, 40, 51, and 66, respectively. Causes of death were right ventricular failure in a patient with preoperative massive right ventricular infarction (day 1), cardiac arrest (day 40), and multiple organ failure (days 9, 51, and 66). All deaths occurred in group 1 (5/25; 20%), but no patients in group 2 died. The logistic EuroSCORE predicted mortality was 36.8 % for group 1, and 15.2 % for group 2 (Table 3).
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Hospital Morbidity
Complications included immediate reoperation for right ventricular assistance (extracorporeal membrane oxygenation) in 1 patient with massive preoperative right ventricular infarction, mediastinitis in 2 patients in group 2, reoperation for bleeding in 1 patient from group 1, and pulmonary infection in 12 patients, including 8 patients in group 1 and 4 patients in group 2. No complications related to IABP occurred.
A cerebrovascular accident occurred in 1 patient in group 1. Right hemiplegia developed after partial clamping of the left brachiocephalic artery for proximal anastomosis of a vein graft in a porcelain aorta. The patient was obese (body mass index, 32) was receiving corticotherapy for chronic obstructive pulmonary disease, and emergency status contraindicated the use of two mammary arteries. This patient died from multiple organ failure at day 66.
The mean duration of hospitalization was 21.6 ± 15.4 days in group 1 and 16 ± 6.9 days in group 2 (p = NS). The mean intensive care unit stay was 12 ± 17 days in group 1 and 5 ± 2 days in group 2 (p = NS). The mean postoperative IABP time was 2.6 ± 1.3 days in group 1 and 1.6 ± 0.7 days in group 2 (p < 0.05).
Mid-Term Follow-Up
Follow-up was achieved for all survivors (mean follow-up, 24 months). Two patients died during follow-up: 1 patient in group 1 from pulmonary neoplasm after 7 months, and 1 patient in group 2 from terminal renal insufficiency after 7 months. A 46-year-old woman in group 1 underwent cardiac transplantation after 14 months for persistent cardiac insufficiency. Among the other survivors, 32 patients are in New York Heart Association functional class I, 14 are in class II, and 1 is in class III. One patient from group 2 underwent a subsequent percutaneous coronary intervention for progressive disease of the right coronary artery after 14 months. No major cardiac event due to incomplete revascularization was reported during follow-up.
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Comment |
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Preoperative IABP is also advocated in high-risk groups and has proven reduced mortality compared with perioperative or postoperative insertion [1, 2, 5, 6]. The reduction in mortality can be explained by the diminution of left ventricular afterload, the increased cardiac index, and the enhanced coronary diastolic blood flow [2, 3]. For the same reasons, IABP allows easier management of the patients during off-pump procedures.
Our current practice is to perform systematic off-pump operations for all isolated coronary procedures, representing a group of 1300 consecutive patients for 5 years and with a 3% conversion rate to extracorporeal circulation. Since March 2000, only 5 patients (0.4%) were admitted to the operating room for an on-pump procedure. These patients presented with cardiogenic shock, which necessitated external cardiac massage and excluded an off-pump operation.
Because some studies have already described the beneficial effects of preoperative IABP insertion and off-pump operation, we have used this combined approach from May 2000 at our center. We designed our study to prospectively compare the results in two groups of patients using a validated predictive model of mortality (EuroSCORE) [13]. We were not able to compare our results with an historical group of patients operated on off-pump without preoperative IABP because our off-pump program started only 3 months before the first case enrolled in this study.
The indications for preoperative IABP implantation were very restrictive because of the potential detrimental effects associated with the use of the device [15, 16]. In the elective group, selected criteria were an ejection fraction of less than 0.30 in patients requiring revascularization of the lateral and posterior wall, or patients with electrical anomalies at rest related to 90% stenosis of the left main trunk and in whom the IABP device was inserted to delay the revascularization for 24 hours so it could be done under more stable conditions. In the emergency group, the inclusion criteria were patients needing emergency interventions because of cardiogenic shock requiring maximal inotropic support, evolving infarction, or unstable angina despite maximal adequate therapy. In this population, the IABP was inserted as soon as possible after the decision to operate was made because of the significant impact on the prognosis of these patients. In the elective group, the IABP was inserted the day before the operation.
The optimal timing for insertion of the IABP preoperatively was well demonstrated by Christenson and colleagues [14]. A 24-hour preoperative period of IABP treatment was found to result in a better postoperative cardiac index than shorter treatment of 1 to 2 hours of preoperative IABP support, with no impact on hospital mortality or postoperative morbidity. Conversely, intraoperative or postoperative IABP insertion has been disappointing owing to an associated high mortality rate and a high device-related complication rate [1].
No complications due to IABP were observed in our study, despite the presence of peripheral vascular disease in 27% of the patients. This result can be attributed to the technical improvements in the device and to the reduction in the size of the device from 9.5F to 8F, and recently to 7.5F [15, 16]. Also, the IABP is now used without a sheath to lower the secondary effects on peripheral arterial flow.
Another explanation could be that elective insertion of IABP in stable patients minimizes the malperfusion effects encountered when the device is inserted in patients who are already hemodynamically critical. Avoiding high inotropic support in these patients could prevent visceral and peripheral malperfusion.
In our experience, more liberal use of preoperative IABP did not change the total rate of device insertion but led to a decrease in the postoperative insertion indications and, more important, a reduction in postoperative mortality (Fig 2).
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In our experience, aortoiliac arteriography is performed in the catheterization laboratory before the device is positioned. Anticoagulation with heparin is achieved in unstable patients and with preventive doses of fractionated heparin in elective patients. The IABP was removed 1.6 days after the procedure in group 2 and as soon as hemodynamic stability was restored (cardiac index > 2l/min) in group 1 (mean duration, 2.6 days).
Conversion to extracorporeal circulation occurred in 5 patients, which was higher than the 3% conversion rate observed in our group of 1300 consecutive OPCAB patients; but this remains acceptable when the characteristics of the high-risk patients are taken into account. Our policy is to use extracorporeal circulation before the appearance of severe hypotension or rhythm disturbances and to perform secure anastomoses to ensure perfect myocardial revascularization [17].
The overall observed mortality was reduced by 67% when compared with the EuroSCORE. In group 2, the results were even better, as no deaths occurred, and the predicted mortality was 15.2% for this group. Reduced mortality with off-pump procedures were reported by Stamou and colleagues [9] in a retrospective review of all patients with a Parsonnet score greater than the 75th percentile undergoing coronary bypass grafting. They found that the risk of 30-day mortality was 2.10 times greater in the on-pump group than in the off-pump group. Moreover, the OPCAB benefit extended beyond the early risk phase (the first year) and was not associated with an increased mortality in the mid-term interval.
The number of anastomoses per patient in our study was similar to that in our current practice, as complete revascularization remains the principal advantage of cardiac operations and is essential in these patients. In a prospective randomized trial, Puskas and colleagues [10] demonstrated that the completeness of revascularization in OPCAB versus conventional operations were similar (3.4 ± 1 anastomoses for both). Once the postoperative phase is achieved, our mid-term follow-up shows excellent clinical results, with no subsequent revascularizations due to incomplete procedures or any deaths of cardiac origin, thus confirming the adequacy of the revascularization [18].
In conclusion, this study presents our strategy for high-risk patients undergoing coronary intervention. Preoperative IABP therapy associated with off-pump operations was effective in reducing hospital mortality compared with EuroSCORE-predicted mortality. Preoperative insertion of IABP was not associated with postoperative complications in our groups of patients. Furthermore, by maintaining stable hemodynamics during the procedure, the IABP procures safe access to the lateral and posterior wall of the heart during off-pump interventions, allowing the complete revascularization essential to optimal long-term results. Combined use of the two techniques resulted in a 62% reduction in mortality compared with the EuroSCORE-predicted cumulative mortality.
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References |
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TopAbstractIntroductionPatients and MethodsResultsCommentReferences |
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Related Article
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  A. Miceli, B. Fiorani, T. H. Danesi, G. Melina, and R. Sinatra Prophylactic intra-aortic balloon pump in high-risk patients undergoing coronary artery bypass grafting: a propensity score analysis Interactive CardioVascular and Thoracic Surgery, August 1, 2009; 9(2): 291 - 294. [Abstract] [Full Text] [PDF]
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 J. T. Christenson Invited commentary Ann. Thorac. Surg., August 1, 2007; 84(2): 502 - 503. [Full Text] [PDF]
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