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J Thorac Cardiovasc Surg 1997;113:173-181
© 1997 Mosby, Inc.

CARDIOPULMONARY BYPASS, MYOCARDIAL MANAGEMENT, AND SUPPORT TECHNIQUES

A COMPARISON OFTHE EARLY AND MIDTERM RESULTS AFTER DYNAMIC CARDIOMYOPLASTY IN PATIENTSWITH ISCHEMIC OR IDIOPATHIC CARDIOMYOPATHY

Ouz Tademir, MD^a, Süha D. Küçükaksu, MD^a, Kerem M. Vural, MD^a, Fehmi S. Katirciolu, MD^a, Emine Kütük, MD^b, Kemal Bayazit, MD^a

Received for publication Oct. 19, 1995 revisions requested Dec. 5, 1995 Revisions received August 2, 1996 Accepted for publication August 8, 1996 Address for reprints: Ouz Tademir,MD, Türkiye Yüksek htisas Hastanesi, KardiovaskülerCerrahi Klinii, 06100, Sihhiye, Ankara, Turkey.

Abstract

Objective: The main goal of this study is todetermine the efficiency of the cardiomyoplasty procedure on patientswith cardiomyopathy of different origins (ischemic and idiopathicorigins). Method: Between June 1993 and August 1995, 24patients underwent dynamic cardiomyoplasty with the left latissimusdorsi muscle in our institution. Early and midterm results, as well asthe changes in hemodynamics and functional status during follow-up, werecompared. Results: Early mortality rate was 20.8%(five patients). Concomitant coronary revascularization, a preoperativeleft ventricular ejection fraction below 20%, and a functionalcapacity of class IV (intermittently) were associated with earlymortality. The mean follow-up time was 17.3 months. Survival analysis(including early mortality) extending to the twenty-fourth monthrevealed no difference between the ischemic and idiopathic groups(55% vs 85%, respectively, p = 0.09). Functional status improved inthe both groups. Ejection fractions were improved after cardiomyoplastyin all patients, regardless of their cause. Cardiac indices were higher6 months after the operation. Changes in pulmonary capillary wedgepressure, peak pulmonary artery pressure, and left ventricularend-diastolic volume were not significant. Conclusion: Although cardiomyoplasty improvesfunctional capacity and hemodynamics in patients with both idiopathicand ischemic cardiomyopathy, the idiopathic group is thought to achieveoptimal benefit with regard to lower complication rates and lower earlymortality expectancy owing to the absence of concomitant coronaryrevascularization. (J Thorac Cardiovasc Surg1997;113:173-81)

Since the first clinical application ofcardiomyoplasty in 1985, ¹ determining the patient group expected to havethe maximum benefit after the procedure has been a major concern in manyclinical and experimental trials. Although dynamic cardiomyoplasty hasbeen performed on more than 500 patients and results in groups withdifferent causes for cardiomyopathy have been reported, the efficacy ofdynamic cardiomyoplasty in the separate groups still needs to beclarified. In this study, we compared the early and midterm courses ofour patients with ischemic and idiopathic origins for cardiomyopathywith regard to operative mortality, survival, functional capacityimprovement, and certain clinical and hemodynamic parameters.

Patients and methods

Between June 1993 and August 1995, 24 patients underwentdynamic cardiomyoplasty with the left latissimus dorsi muscle in ourinstitution. Two of the patients were female. The mean age was 43± 9 years. All patients were in New York Heart Associationfunctional class III (six patients had been admitted to the hospitalwith class IV symptoms and had improved to class III with vigorousmedical treatment). Our patient population was divided into twosubgroups depending on the causes of the disease: ischemiccardiomyopathy group (11 patients) and idiopathic cardiomyopathy group(13 patients). Ischemic cardiomyopathy was diagnosed by the occurrenceof a dilated cardiomyopathy and documented coronary artery stenosis ortypical enzymatic and electrocardiographic criteria for a previousmyocardial infarction. The diagnosis of idiopathic dilatedcardiomyopathy was assigned only to patients with angiocardiographicallynormal coronary arteries and no other obvious cause for left ventriculardysfunction. There was no statistically important difference between thetwo groups regarding age and preoperative clinical or hemodynamiccondition (Table I). Operativeindications and contraindications and the surgical technique were thesame as described by Carpentier and Chachques and theirassociates. ^2,3

The use of prophylactic intraaortic balloon (IAB) supportto improve patient stability during the procedure and in the earlypostoperative course seemed appropriate. Therefore, in the last 11patients (two of the ischemic group and nine of the idiopathic group),we routinely inserted an IAB just after the induction of anesthesia. IABcounterpulsation lasted 1 or 2 days after the operation.

A Medtronic Cardiomyostimulator (model SP 1005A and model4710; Medtronic, Inc., Minneapolis, Minn.) with a stimulation protocoldescribed by Chachques, Grandjean, and Carpentier ⁴ was used.

The mean follow-up time for the total cardiomyoplasty groupwas 17.3 months. Statistical analyses were performed by a certifiedstatistician. The tests used for each item are described in the relatedpart of the Results section. Survivalcurves are estimated by means of the Kaplan-Meier method and compared bymeans of the log rank test. Because functional class is on a scale fromI to IV, it is unlikely that the necessary distributional assumptionsfor a standard variance analysis will hold. Similarly, inadequate numberof cases on the basis of ischemic and idiopathic subgroups necessitatednonparametric tests for comparison of the ejection fractions andfunctional status at certain follow-up periods. Therefore the Wilcoxonmatched-pairs signed-rank test was used for performing pairwisecomparisons of ejection fractions and functional capacities during thefollow-up period. With this test we compared all possible pairs during agiven follow-up period (e.g., preoperative to third postoperative month,preoperative to sixth postoperative month, third to sixth postoperativemonth) for the total group (appendix). Comparisons of these data betweenthe ischemic and idiopathic groups at each follow-up period wereperformed with the Mann-Whitney U test. With this test we compared thedifferences from the baseline (preoperative) values for the ejectionfractions or average functional classes from the two subgroups (ischemicand idiopathic) at the same follow-up period. For this purpose, theejection fraction or functional class values obtained at postoperativemonths 3, 6, 12, and 24 were subtracted from the preoperative value. Thechanges from the preoperative period for each postoperative intervalwere obtained for both groups (idiopathic and ischemic). Then, using theMann-Whitney U test, we compared these adjusted values (the change fromthe preoperative period) from those two subgroups (e.g., the differenceat the third postoperative month for the idiopathic group was comparedwith that of the ischemic group). Because this is a multiple comparisonsituation (with ten comparisons in the total group between the periodsduring the follow-up and four between the subgroups at the same period),an adjustment for the p value wasnecessary. An adjusted p value ()may be calculated as follows: For the pairwise comparisons for theejection fraction or functional class improvement in the total groupduring follow-up (i.e., Wilcoxon matched-pairs signed-rank test), = 0.05 / 10 = 0.005. For the comparisons between the ischemicand idiopathic subgroups at each follow-up period (i.e., Mann-Whitney Utest), = 0.05 / 4 = 0.013. Any significance depending on theseadjusted p values is indicated in theappendix.

Univariate analysis for determining the factors associatedwith early hospital mortality was performed with Fisher's exact test.Proportions such as mortality rates are compared with the² test. A p value equalto or smaller than 0.05 was considered as statisticallyimportant.

Results

Mortality
There were five early and two late deaths (30-day hospitalmortality was 20.8%). Early hospital mortality rate was36.3% in the ischemic group and 7.6% in the idiopathicgroup. The difference between these two mortality rates did not reachstatistical significance (p = 0.11).

As seen in Table II, in the early postoperative period, onepatient from the idiopathic group died of low cardiac output.Four patients from the ischemic group died (two of low cardiac output,one of cerebral embolism, and another of Klebsiella pneumonia and sepsis). Three of thosefour patients with ischemic cardiomyopathy who died in the earlypostoperative period had also undergone concomitant coronary bypassgrafting.

Incremental risk factors forearly hospital mortality
Univariate analysis (Fisher'sexact test) was performed for the total group to determine theparameters associated with early hospital mortality. Age, type ofcardiomyopathy (ischemic or idiopathic), concomitant coronaryrevascularization, prophylactic IAB support, a preoperative leftventricular ejection fraction below 20%, preoperative spirometricdata below 50% of predicted, severe preoperative rhythmdisturbances, preoperative functional classes (i.e., class III vsintermittent class IV), and preoperative left ventricular end-diastolicpressures were the factors to be analyzed for any association with earlymortality. Univariate analysis indicated the associated coronary bypassprocedure (p = 0.018), a class IVfunctional capacity (intermittently) (p= 0.018), and a preoperative left ventricular ejection fraction below20% (p = 0.0013) as the factorsassociated with early mortality (Table IV).

View larger version (46K): [in this window] [in a new window]   Fig. 1.Postoperative survival (including early hospital mortality)in patients with ischemic or idiopathic cardiomyopathy. Patient numbersentering each period from each group are described below theillustration. Idiop., Idiopathic;Ische., ischemic.

Comparison of preoperative andpostoperative hemodynamic data
Ejection fraction
The Wilcoxon matched-pairs signed-rank test was used forpairwise comparisons of ejection fractions during the follow-up periodin the total group. A statistically important improvement was evident inthe third, sixth, twelfth, and twenty-fourth postoperative months (seethe appendix for exact p values) whencompared with preoperative values (Table V and the appendix). TheMann-Whitney U test was used to compare the ejection fraction changesbetween the ischemic and idiopathic subgroups from the preoperativeperiod onward. No significant difference was found at any follow-upperiod (appendix). In other words, ejection fraction trends for theischemic and idiopathic groups were roughly parallel in the first 2years.

Functional class
The Wilcoxon matched-pairs signed-rank test was used forpairwise comparisons of average functional classes during the follow-upperiod in the total group. A statistically important improvement wasevident in the third, sixth, twelfth, and twenty-fourth postoperativemonths when compared with preoperative functional classes (see theappendix for exact p values). Acomparison between the ischemic and idiopathic groups was done with theMann-Whitney U test at each follow-up period, as explained in thePatients and methods section. Nosignificant difference between the subgroups was found at anypostoperative time interval (appendix).

Preoperative mean functional class of 3.2 was improved to1.3 after 2 years. This means an improvement of 60% in averagefunctional class (Figs. 2 and 3).

View larger version (31K): [in this window] [in a new window]   Fig. 2. Thecourse of functional classes in the idiopathic group. NYHA, New York Heart Association.

View larger version (35K): [in this window] [in a new window]   Fig. 3. The course of functional classes in theischemic group. NYHA, New York HeartAssociation.

Various surgical methods have been proposed to treatend-stage heart disease. Transplantation and artificial organs have beenused in these patients in limited numbers because of the scarcity ofavailable donor organs for transplantation and clotting problems inartificial organs. Unavailability of donor organs resulting fromsocioeconomic problems and the lack of adequate infrastructure andorganization strictly limit transplantation possibilities, especially inTurkey.

The idea of cardiomyoplasty is to wrap the latissimus dorsimuscle around the heart and to bring extra support both passively anddynamically while simultaneously contracting the muscle with themyocardium to augment the generated power. Contribution of thelatissimus dorsi to cardiac activity may vary with the nature of theheart disease. We compared the outcome of patients undergoingcardiomyoplasty for two different types of cardiomyopathy to investigatethe efficacy of the procedure. One group consisted of 11 patients withischemic cardiomyopathy and the other consisted of 13 patients withidiopathic cardiomyopathy.

Age, prophylactic IAB pumping, preoperative spirometricdata below 50% of predicted, severe preoperative rhythmdisturbances, and preoperative left ventricular end-diastolic pressureswere found to be the factors having no important influence on earlymortality. Univariate analysis indicated an associated coronary bypassprocedure, a class IV functional capacity (intermittently), and apreoperative left ventricular ejection fraction below 20% as thefactors being associated with early mortality. Our relatively high rateof early mortality in the ischemic group might have been influenced bythe associated coronary artery bypass procedure in this group. For moredetailed information, logistic regression analysis could be performedafter a sufficient number of cases for this analysis was obtained.

Many studies emphasize various incremental risk factors forearly mortality. In a study by Magovern and associates, ⁵ biventricular failure(especially with a right ventricular ejection fraction lower than40%) was described as an important risk factor for earlymortality. Biventricular failure was emphasized as a contraindicationfor cardiomyoplasty in the study by Carpentier and colleagues. ²

In our patient population, the course in the intensive careunit was more complicated for the ischemic group than for the idiopathicgroup. Furthermore, concomitant surgery is frequently required inpatients with ischemic heart disease, bringing additional problems thatinfluence both mortality and morbidity. Carpentier and associates ² documented that concomitantsurgery is an incremental risk factor in the cardiomyoplasty population.Lorusso and associates ⁶operated on nine patients without any associated procedure, and only oneof their patients died—as a result of respiratory distresssyndrome in the first postoperative month. However, in some reportsearly mortality was found to be independent of associated surgicalprocedures. ⁷

Minimal doses of inotropic drugs in combination with theperioperatively inserted IAB is logical in the cardiomyoplastypopulation, a group in which high perioperative risk is anticipated.Although statistical analysis revealed no effect on early mortality,prophylactic IAB support during the operation and for the first 48 hoursof the postoperative period still seems logical to provide a smootherpostoperative course and a more comfortable course during the surgicalprocedure. Of the last 11 patients with a prophylactic, preoperativelyinserted IAB, only one patient died (of a noncardiacevent—sepsis). On the other hand, of the 13 patients without thisprophylactic measure, four died (three of low cardiac output). Thereforewe advise the prophylactic perioperative insertion of an IAB as aroutine procedure. However, especially in patients with ischemiccardiomyopathy, a full Doppler evaluation of the lower extremityperipheral arteries should be done before considering such prophylacticuse of the IAB, because of the extensive nature of the atheroscleroticprocess.

Follow-ups extending to the twenty-fourth postoperativemonth showed no statistically important difference in the Kaplan-Meiersurvival analysis between the ischemic and idiopathic groups.

Left ventricular ejection fractions are improved aftercardiomyoplasty. Between the subgroups, postoperative trends in theejection fractions were roughly parallel during the follow-up period.Improvement in the ejection fractions without significant change in leftventricular end-diastolic volumes suggested some beneficial effects ofcardiomyoplasty.

A statistically important improvement in functional class(an improvement of 60%) for the total cardiomyoplasty populationwas established. This improvement did not differ in degree for the twoetiologic subgroups.

Although no differences in objective (ejection fraction) orsubjective (functional status) criteria were detected during thepostoperative follow-up period between the two groups, the idiopathicgroup is thought to obtain optimal benefit with regard to lower earlycomplication rates and lower early mortality expectancy. The advantageis that these patients do not need concomitant coronaryrevascularization, which is associated with early mortality.

In our study, the early mortality rate for the ischemicgroup was 36.3% whereas it was 7.6% in the idiopathicgroup. This difference did not reached statistical significance withFisher's exact test (p = 0.11), whichwas used for the analysis of the factors to be associated with earlymortality in this study. On the other hand, when another test(comparison of two proportions, z-test) is done, the p value reached 0.04. This difference may be dueto the relatively low number of cases, and tests must be repeated aftermore cases are available for analysis. Thus better results may beexpected in the idiopathic group in terms of early mortality andcomplication rates. This could probably be attributed to the differencein nature between the two etiologic conditions. Metabolic imagingstudies in the ischemic cardiomyopathy group had revealed large defectscovering more than 15% of the cross-sectional area of the leftventricle; however, such large defect zones had only rarely beenobserved in nonischemic cardiomyopathies. ⁸ Residual function of the heart may be animportant factor in the overall performance of the dynamiccardiomyoplasty. ⁹ Thismight explain why dynamic cardiomyoplasty has been reported to be lessefficient in such severe myocardial dysfunction.

In the light of the current study, we believe that risk isgreater in ischemic than in idiopathic cardiomyopathy as a result of thepathophysiologic differences, as well as additional risks from theexpected concomitant procedures (i.e., coronary bypass grafting). Hencehigher mortality and morbidity could be expected in the earlypostoperative period. However, after a certain period of convalescence,the courses for the two groups became parallel. The data contain onlythe midterm results, and later follow-up will supply more informationabout the long-term prognosis of patients with different underlyingcauses.

In conclusion, in our 24-patient cardiomyoplasty group, wefound an improvement in ejection fractions and in functional classes atthe end of a follow-up period of 24 months. Survivals did not differbetween the idiopathic and the ischemic subgroups. The current studyconsiders early and midterm results. Because of the progressive natureof the disease, long-term results must also be obtained to clarifyobscured points and perhaps to accentuate the possible differencesbetween the etiologic subgroups that are currently not apparent.

Addendum

Since the submission of this manuscript, seven morepatients have successfully undergone dynamic cardiomyoplasty in ourinstitution. Hence our cardiomyoplasty experience has currently reached31 cases. However, because the statistical interpretation of thesepatients has not been performed at this time, related data are notincluded in this study.

Appendix: Commentary

This article reports the institutional experience of the authors with cardiomyoplasty. It is of interest because it indicates how the results claimed by the pioneering centers can be reproduced by others. The authors also attempted to analyze the outcome using the cause of cardiomyopathy (ischemic vs idiopathic) as a variable. However, such institutionally based data also suffer from some limitations. The obvious one in this series is the small sample size, which reduces the statistical power. For example, the hospital mortality for the ischemic group was 36.3%, almost five times that of 7.6% for idiopathic group, but the difference did not reach statistical significance (p = 0.11). Likewise, they reported no difference in 24-month survival (p = 0.09) between these two groups, even though the survivals were 55% versus 85%. Another weakness with small sample size is the difficulty in carrying out subgroup analysis. In this series, 24 patients were divided into two groups: 13 in the idiopathic and 11 in the ischemic group. In fact, the ischemic group contains four patients who underwent concomitant coronary revascularization, an important confounding factor that was not analyzed, perhaps because the number of patients was too small to do so.

View larger version (33K): [in this window] [in a new window]   Fig. 1. Survival of idiopathic versus ischemic group.

Ray C.-J. Chiu, MD, PhD
McGill University
Montreal, Quebec, Canada

Footnotes

From Cardiovascular Surgery^a Cardiology^bDepartments at Türkiye Yüksek htisas Hospital, Ankara, Turkey.

References

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3. Carpentier A, Chachques JC.Cardiomyoplasty: Surgical technique. In: Carpentier A, Chachques JC,Grandjean P, editors. Cardiomyoplasty. Mount Kisco [NY]: Futura,1991:105-22.
   
4. Chachques JC, Grandjean PA,Carpentier A. Patient management and clinical follow-up aftercardiomyoplasty. J Card Surg 1991;6(Suppl):89-99.[Medline]
   
5. Magovern JA, Furnary AP, Christlieb IY, Kao RC, Park SB,Magovern GJ. Indications and risk analysis for clinical cardiomyoplasty.Semin Thorac Cardiovasc Surg 1991;3:145-8.[Medline]
   
6. Lorusso R, Zogno M, La Canna G, et al. Dynamiccardiomyoplasty as an effective therapy for dilated cardiomyopathy. JCard Surg 1993;8:177-83.
   
7. Jegaden O, Delahaye F, Finet G, et al. Late hemodynamicresults after cardiomyoplasty in congestive heart failure. Ann ThoracSurg 1994;57:1151-7.[Abstract]
   
8. Geltman EM. Metabolic imaging of patients withcardiomyopathy. Circulation 1991;84(Suppl I):I265-72.
   
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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Oguz Tasdemir Kerem M. Vural Kemal Bayazit Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Tasdemir, O. Articles by Bayazit, K. Search for Related Content PubMed PubMed Citation Articles by Tasdemir, O. Articles by Bayazit, K.