35 EDITORIAL COMMENT

Outcome of Coronary Bypass and Left Ventricular Dysfunction

Insufficient myocardium cell number and muscle specific preoperative factors may help to determine mass seem to be the underlying causes of the optimal treatment (3). dysfunction of the left (LV). In revasculariza- Although patients with severe ventricular tion it is aimed to recover normal functions of alive dysfunction have improved long-term survival times myocardium cells that were dysfunctioning under is- after coronary bypass procedures, operative morbi- hemic conditions due to coronary obliteration. dity and mortality rates remain high. A report from The technological developments in the recent ye- Canada by Christakis GT et al. (4) identified the con- ars and the improvements in the coverage of the pa- temporary risk factors for isolated CABG in this high- tient influenced myocardial revascularization in a po- risk subgroup. Study included a total of 12,471 pati- sitive way. The survival rates have increased. Many ents underwent isolated CABG. Among 3 study gro- risk factors which have been accepted as contraindi- ups, patients with preoperative EFs greater than cation for coronary revascularization in recent years, 40% had a lower operative mortality rate (2.3%) are no handicap anymore nowadays (1, 2). than that of the patients with EFs between 20% and Thus, it is found out that other treatment moda- 40% (4.8%) and that of those with EFs less than lities should be reviewed in the coronary artery dise- 20% (9.8%). However, patients with EFs of less than ase with low function of the ventricle. Milano CA et 20% were demographically distinct from those with al. (3), reported a study including patients with ejec- higher EFs. This group was older, with fewer wo- tion fraction (EF) less than or equal to 0.25 under- men, a higher frequency of left main stenosis, and went isolated coronary artery bypass grafting more frequent requirement of urgent operation for (CABG). The study evaluated whether patients with unstable angina. The traditionally accepted risk fac- and severely depressed LV EF tors--urgency of operation, left main coronary artery would benefit from CABG. Operative mortality was stenosis, reoperation, sex, and age--were predictive 11%. Survival at 1 year and 5 years was 77.2% and of risk of operative death for patients with EFs gre- 57.5%, and was better than estimated survival with ater than 40%. The risk of operative death for pati- medical therapy alone. Survivors experienced signifi- ents with EFs between 20% and 40% was predicted cant improvement in angina class, congestive failure by urgency of operation, reoperation, gender, myo- class, and follow-up EF. Of 22 preoperative factors cardial protection, and age. The only predictor of evaluated by univariate survival analysis, five were risk of operative death for patients with EFs less than 20% was urgency of operation (4). associated with significantly greater mortality: pre- Patients undergoing isolated CABG who have sence of other vascular disease, female gender, severe ventricular dysfunction are therefore a highly hypertension, elevated LV end-diastolic pressure, selected, high-risk subgroup of patients whose risk and depressed cardiac index. Considering length of depends on the urgency of operation. Strategies to hospitalization, three factors showed significant ad- improve the results in these patients should be focu- verse effect in a multivariate Cox model: time on car- sed on patient selection, improvement of myocardial diopulmonary bypass, acute presentation, and fema- protection, and more aggressive preoperative treat- le gender. These data and review of the literature ment of myocardial ischemia. Due to inoperability, suggest that patients with coronary artery disease the thought of the high percentage of the operation and severely depressed EF benefit from CABG, and mortality, or the poor distal coronary arterial bed, Yaz›flma Adresi: Prof. Dr. Azmi Özler more patients with the coronary artery disease are re- Kalam›fl Fener Cd.9/3 Nur Apt. ferred to transplantation. It is known that the five ye- K›z›ltoprak ‹STANBUL Fax:0216 4143297 ars survival rate of transplantation is about 70% (5). A.Özler Ana Kar Der 36 Coronary Bypass Surgery and Left Ventricular Dysfunction 2002;2: 35-39

Heart transplantation is another effective treat- Does the manipulation of the during off-pump ment modality. Raising the rate of survival and incre- coronary artery bypass (OPCAB) procedure further asing the quality of life after transplantation depend compromise the hemodynamic stability of a patient on a secure immunosuppression and a better covera- with depressed LV function compared with the con- ge of the patient. Compared to the medical treatment ventional coronary artery bypass (CCAB) approach? the results are much better (6). The difficulties accom- Does this manipulation induce a more dramatic panying the transplantation, namely immunosuppres- hypoperfused state that may contribute to an incre- sion, dependence of the patient to hospital for the ase in the incidence of related complications or mor- rest of his life, need for a close follow-up and the high tality? Arom KV et al’s (11) retrospective review of probability of rejection make it a treatment far from data attempted to answer the above concern. Despi- ideal and research for ideal treatment is still going on. te recognized hemodynamic derangement during Yet another adjuvant treatment modality for cardiac displacement, these groups of OPCAB pati- dispute group of high surgery risk and poor LV coro- ents appeared to tolerate the procedure well. Multi- nary artery disease patients is transmyocardial laser vessel coronary artery bypass utilizing the OPCAB revascularization (TMLR). Lutter G et al. (7) applied approach in patients with depressed LV function of comparison study with 23 end-stage coronary artery equal to or less than 30% is appropriate and appli- disease patients who were treated with TMLR as so- cable. Attention to intraoperative details and he- le therapy without the use of IABP. The creation of modynamic management could be credited for the transmural channels was performed by a CO2-laser. success with OPCAB (11). Previous reports have de- All patients were evaluated by hybrid positron emis- monstrated that reoperative coronary revascularizati- sion tomography (perfusion SPECT and viability PET) on, advanced age, female sex, and impaired LV and ventriculography preoperatively. The perioperati- dysfunction are independent predictors of operative ve mortality of this combined procedure (TMLR and mortality after CABG. Coronary artery bypass graf- IABP) was zero. The reported data support the con- ting without (off-pump cept to start IABP preoperatively in patients with re- CABG) has been proposed as a potential therapeutic duced LV contractile reserve in order to provide car- alternative in these high-risk patient groups (12). diac support during the postoperative phase of re- Despite the substantial learning curve associated versible decline of LV function induced by TMLR (7). with off-pump CABG, early outcomes of off-pump Conventional CABG using cardiopulmonary CABG in high-risk patients are better than those as- bypass carries relatively high mortality and morbidity sociated with the conventional on-pump CABG app- for patients with LV dysfunction. Coronary artery roach. These results suggest that off-pump CABG is bypass grafting without cardiopulmonary bypass is a a safe alternative to on-pump CABG in high-risk pati- viable alternative to conventional CABG particularly ents. Randomized prospective studies are needed to for patients with extreme LV dysfunction or those validate the results of these initial retrospective re- with coexisting risk factors, such as acute myocardi- ports and to demonstrate the long-term benefits of al infarction and cardiogenic shock (8). this approach (12). Arom KV et al. (9) from Minneapolis, analyzed There are different ideas whether viability tests outcomes of 387 patients with normal and poor are necessary preoperatively or not. Concerning the LVEF underwent off-pump coronary artery bypass coronary artery patients with low EF (<30% or 20%), (OPCAB) procedure. The two groups (LVEF < or =30 it is beneficial to display the pre-operative viability and LVEF>30) were compared using univariate analy- and graftabilty or akinesis-dyskinesis. sis. Short-term clinical outcomes for both groups of Wiggers H et al. (13), reported a study on uti- OPCAB patients are encouraging and allow continu- lity of different algorithms of identification of pati- ing to offer this approach to the broad patient popu- ents with heart failure who could potentially benefit lation (9). According to Baumgartner FJ, there is a from revascularization. Thirty-five coronary artery significant reduction in intraoperative blood transfu- bypass (graft) patients with an EF of 35±7% under- sion requirements, as well as a significant reduction went preoperative 18F-fluoro-2-deoxyglucose posit- in the incidence of neurologic, renal, and prolonged ron emission tomography (PET), low-dose dobutami- ventilatory complications in the off-pump group (10). ne (LDDE), and exercise testing. There are yet another challenging questions. Follow-up by echocardiography and coronary angi- Ana Kar Der A.Özler 2002;2: 35-39 Coronary Bypass Surgery and Left Ventricular Dysfunction 37

ography was performed 6 months after CABG. The (14) results with the findings of this study, displays si- sensitivity for prediction of reversible myocardial milarity with the standard group regarding the pati- dysfunction was highest for PET and for ST depressi- ent profile and the method used. However, ‹slamo¤- on or angina pectoris during exercise testing (93%). lu F et al. (14) reported mortality rate as 5.6%, per- The specificity did not differ between LDDE (81%), op MI - 1.58%, post-op IABP usage- 3.57% and post- PET (67%), and resting ECG (71%), but was lowest op LCO - 3.57%. for exercise testing. In patients with a negative exer- The striking differences between the study of ‹s- cise test, recovery was unlikely, and further viability lamo¤lu F et al. (14) and the previous studies are: testing may not be needed. In patients with a positi- 1. In the previous studies, the criteria for dama- ve test, recovery may occur, and additional PET or ged left ventricule function is taken to be EF<20%, LDDE should be performed. This strategy awaits furt- for ‹slamo¤lu F et al. the criteria is EF<30%. her evaluation in larger patient populations with he- 2. In similar studies, LV scar tissue and its surgical art failure (13). intervention have been included in the mortality, In the article submitted by ‹slamo¤lu F et al. (14) whereas in ‹slamo¤lu F et al. study cases with vent- and published in this issue of the Anatolian Journal Of ricular aneurysm have been excluded. Cardiology, (that aimed to search for the effects of The working period (5 years) and the large num- pre-operative risk factors on mortality resulting from ber of patients which fit the research criteria have set coronary artery by-pass surgery without having made the stage for more objective statistical results in the a prior viability test applied on 252 coronary artery presented prospective study. Looking at the patient patients suffering from damaged ventricular function profile, observed better renal performance (renal fa- (EF<30%)), the results have shown that hospital mor- ilure 0.8%) and a lower pre-operative IABP usage tality is 5.6%, average 4 year survival rate is recorded (0%) in patients with low LV function (EF<30%) are to be 78%. In a similar study, the results of a prospec- interesting. tive analysis carried on 72 patients have come out to Comparative analysis allows to reveal why results be 3.8% for hospital mortality and 5 year survival ra- obtained by ‹slamo¤lu F et al. are clearly superior te 68% (15). Looking at the profile of the patients, than those found in literature. Moreover, it is suffici- for the published study of ‹slamo¤lu F et al. (14) is ent by itself to open the debate on the necessity of expected to be lower, the outcome is nearly twice as using an additional modified myocardial protection that of the other study regarding the hospital morta- method (Temperature Mapping ). Ho- lity rates. Probably, the reason for that may be arising wever, according to this study, while the surgical from surgical strategy. Mickleborough LL et al. later strategic differences that bring about the absolute on published a study comparing two groups of 125 success are not defined, pre-operative viability rese- patients with low EF’s based on the surgical strategy arch is emphasized as unnecessary. difference (16). In their experiment, two patient gro- In the light of the results of recent studies preva- ups operated with two different myocardial protecti- iling in literature; LV hypertrophy (LV size) and low on techniques named “Temperature Mapping Cardi- EF (20%) are mentioned as the pre-operative risk fac- oplegia (TMC)” and standard technique have been tors in coronary artery disease (17). In patients with compared for the effects of preoperative risk factors poor ventricular function and with chamber dilation, on mortality and morbidity post-operatively. In the ex- it is not possible by preoperative conventional ventri- perimental group, mortality and morbidity rates were culography to determine which areas of the heart found to be lower than in the control group. Tempe- are scarred and will take advantage of partial ventri- rature Mapping Cardioplegia method have yielded culectomy-aneurysmectomy (18). Some centers re- the following results: hospital mortality is 4%, perop- commend use of pre-operative viability tests for cho- myocardial infarction (MI) 4%, post-op IABP usage ra- osing patients for revascularization (19-21). te 15%, post –op low cardiac output syndrome Patients without supply-demand disorder and (LCO) 19%. However, the values recorded for the without an evident dyskinesis are considered as bad standard group (where standard cardioplegia met- candidates for surgery. Those patients having a graf- hod was applied) were higher, hospital mortality table coronary artery with poor ventricular function 11%, perop MI 7%, post-op IABP usage 30%, post- and akinetic-dyskinetic ventricle benefit from surgery op LCO is 30%. Comparison of ‹slamo¤lu F et al. well. A.Özler Ana Kar Der 38 Coronary Bypass Surgery and Left Ventricular Dysfunction 2002;2: 35-39

What’s recommended is to plan the operative References procedure evaluating the regional wall thickness and contractility. If an area has become thin and there is 1. Miller DC, Stinson FB, Oyer PE, et al. Discrimi- scar tissue, ventricular volume should be contracted nant analysis of changing risks of coronary artery by excising the area and geometry should be made operations: 1971-1979. J Thorac Cardiovasc close to normal for optimal ventricular function, wall Surg 1983; 85: 197-213. tension and volume should be decreased. Micklebo- 2. Killip T, Passamani E, Davis K, CASS Principal in- rough LL et al, in one series reported that operative vestigators and their associates. Coronary artery mortality for patients with was low study (CASS): a randomized trial of coronary and acceptable (4%) and five years survival was hig- bypass surgery. Eight years follow-up and survi- her (72%) compared to those without ventriculec- val in patients with reduced EF. Circulation 1985; tomy (14). 72(Suppl 5): 102-9. 3. Milano CA, White WD, Smith LR, et al. Coronary Conclusion artery bypass in patients with severely depres- sed ventricular function. Ann Thorac Surg 1993; Concerning the coronary artery disease pati- 56: 487-93. ents with low EF (<30% or 20%), it is beneficial to 4. Christakis GT, Weisel RD, Fremes SE, et al. Coro- display the pre-operative viability and graftabilty or nary artery bypass grafting in patients with poor akinesis-dyskinesis. In patients with a negative exerci- ventricular function. J Thorac Cardiovasc Surg se test, recovery was unlikely, and further viability 1992; 103: 1083-91. testing may not be needed. In patients with a positi- 5. Stevenson JW, Fowler MB, Shroeder JS, Dracup ve test, recovery may occur, and additional PET or KA, Clark SH,Fond V. Patients denied cardiac LDDE should be performed. transplantation for nonmedical criteria. J Am For such patients any procedure of surgical Coll Cardiol 1986; 7: 9A. grafting (CABG or OPCAB) and if necessary partial 6. Heck CF, Shumway ST, Kaye MP. The registry of ventriculectomy may be done not only easily but al- the International Society for Heart Transplantati- so with low mortality and first option should be sur- on: sixth official report - 1989. J Heart Transplant gical treatment. If viability is lacking, grafting won’t 1989; 8: 271-6. be of any use and it will result even in mortality. 7. Lutter G, Saurbier B, Nitzsche E, et al. Transmyo- Thus, for this group of coronary artery disease pati- cardial laser revascularization (TMLR) in patients ents, is accepted as the first with unstable angina and low ejection fraction. thing. In the future with the advances in application Eur J Cardiothorac Surg 1998; 13: 21-6. of Myocid Regeneration methods, new horizons will 8. Moshkovitz Y, Sternik L, Paz Y, Gurevitch J, Fein- open for those patients. berg MS, Smolinsky AK, Mohr R Primary coro- Modification of advanced myocardial protecti- nary artery bypass grafting without cardiopulmo- on methods (Temperature Mapping Cardioplegia) nary bypass in impaired LV function. Ann Thorac and planning of operation strategy targeting the pa- Surg 1997; 63(Suppl): S44-7. tient (CABG-OPCAB, or hybrid procedures- 9. Arom KV, Emery RW, Flavin TF, Kshettry VR, Pe- TMLR+bypass) will lower the rate of mortality morbi- tersen RJ. OPCAB surgery: a critical review of dity while increasing the long term survival rate in two different categories of pre-operative ejecti- patients with low EF. on fraction. Eur J Cardiothorac Surg 2001; 20: For this group of patients, adding transmyocardi- 533-7. al laser revascularization (TMLR) to surgical revascu- 10. Baumgartner FJ, Yokoyama T, Gheissari A, Capo- larization when needed will again have a positive ef- uya ER, Panagiotides GP, Declusin RJ. Effect of fect on mortality and morbidity and enhancement of off-pump coronary artery bypass grafting on long term survival rates. morbidity. Am J Cardiol 2000; 86: 1021-2. 11. Arom KV, Flavin TF, Emery RW, Kshettry VR, Pe- Dr. Azmi Özler, tersen RJ, Janey PA. Is low ejection fraction safe Dr. Siyami Ersek Gö¤üs Kalp for off-pump coronary bypass operation? Ann Damar Cerrahisi Merkezi, ‹stanbul Thorac Surg 2000; 70: 1021-5. Ana Kar Der A.Özler 2002;2: 35-39 Coronary Bypass Surgery and Left Ventricular Dysfunction 39

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