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Left ventricular function and survival in ischemic cardiomyopathy: Implications for surgical ventricular restoration

Open AccessPublished:March 03, 2021DOI:https://doi.org/10.1016/j.xjon.2021.03.001

      Abstract

      Objectives

      This pilot study evaluates the association of relative wall thickness (RWT) on survival in patients with ischemic cardiomyopathy (ICM). We hypothesized that patients with preserved RWT may be better candidates for surgical ventricular restoration than those with thinner RWT.

      Methods

      Echocardiography was performed in 165 consecutive patients (aged 58.2 ± 14.7 years) divided into 2 groups based on RWT values. Group 1 had patients with preserved RWT and group 2 had patients with reduced RWT.

      Results

      There were 120 (72.7%) patients with hypertension and 112 (67.8%) patients had diabetes mellitus. The patients with preserved RWT (group 1) had significantly more hypertension and diabetes. The patients with decreased RWT (group 2) were in a higher New York Heart Association functional class and had significantly greater incidence of anterior wall myocardial infarction. The entire cohort was followed over 24 months (group 1: n = 117 and group 2: n = 48). The overall all-cause mortality in group 1 (preserved RWT) was 7 (5.9%) and in group 2 (reduced RWT) was 35 (72.9%) (P < .0001). When readmission for congestive heart failure was analyzed, group 2 patients with lower RWT (P < .0001) had an increased rate of readmissions for heart failure.

      Conclusions

      In patients with ischemic cardiomyopathy, a lower RWT indicative of dilated LV remodeling was associated with increased mortality and readmission for heart failure. The RWT may be a simple benchmark of viable or contractile myocardium in ICM. It can be hypothesized that patients with preserved RWT may benefit from surgical ventricular restoration.

      Graphical abstract

      Key Words

      Abbreviations and Acronyms:

      CABG (coronary artery bypass grafting), E/A ratio (early mitral filling velocity/late filling velocity), ESVI (end systolic volume index), ICM (ischemic cardiomyopathy), LV (left ventricle), LVEF (left ventricular ejection fraction), MI (myocardial infarction), NT pro-BNP (N-terminal pro B-type natriuretic peptide), NYHA (New York Heart Association), RFP (restrictive filling pattern), RWT (relative wall thickness), STITCH (Surgical Treatment for Ischemic Heart Failure), SVR (surgical ventricular restoration), TDI (tissue Doppler index)
      Figure thumbnail fx2
      A rectangular intraventricular patch, excluding the left ventricular aneurysm during SVR.
      Preserved relative wall thickness was associated with reduced mortality at 24 months in patients with ICM receiving medical therapy, leading to a hypothesis that it may define responders to SVR.
      In patients with systolic HF, an independent and incremental risk of adverse outcome was associated with increased mass index and decreased RWT. We found that in patients with ICM, preserved RWT was associated with lesser mortality than those with lower RWT. Baseline preserved RWT can be a simple benchmark of viable myocardium, making it an indicator of success for SVR.
      See Commentaries on pages 219 and 221.
      The Surgical Treatment for Ischemic Heart Failure (STICH) trial caused a decline in the practice of surgical ventricular restoration (SVR) for advanced heart failure in patients with ischemic cardiomyopathy (ICM).
      • Jones R.H.
      • Velazquez E.J.
      • Michler R.E.
      • Sopko G.
      • Oh J.K.
      • O'Connor C.M.
      • et al.
      Coronary bypass surgery with or without surgical ventricular reconstruction.
      Although the STICH trial has been criticized by several authors, primarily for its conduct and methodology, SVR has been demonstrated to have efficacy in certain populations with refractory heart failure.
      • Buckberg G.D.
      • Athenasuleas C.
      The STICH trial: misguided conclusions.
      ,
      • Athanasuleas C.L.
      • Buckberg G.D.
      • Stanley A.W.
      • Siler W.
      • Dor V.
      • Di Donato M.
      • et al.
      Surgical ventricular restoration in the treatment of congestive heart failure due to post-infarction ventricular dilation.
      Stringent inclusion criteria are required for the success of SVR, chief of which is presence of a contractile remote myocardium in a preoperative left ventricle (LV).
      In patients with ICM receiving medical management, it was found that patients with preserved relative wall thickness (RWT) had better survival than patients with reduced RWT.
      • Dini F.L.
      • Capozza P.
      • Donati F.
      • Simioniuc A.
      • Corciu A.I.
      • Fontanive P.
      • et al.
      Patterns of left ventricular remodeling in chronic heart failure: prevalence and prognostic implications.
      Those patients with more adverse LV remodeling had worse LV systolic and diastolic dysfunction.
      An LV restrictive filling pattern (RFP) is an index of severe diastolic dysfunction in patients with ICM.
      • Lester S.J.
      • Tajik A.J.
      • Nishimura R.A.
      • Oh J.K.
      • Khandheria B.K.
      • Seward J.B.
      Unlocking the mysteries of diastolic function. Deciphering the Rosetta Stone 10 years later.
      ,
      • Meta-analysis Research Group in Echocardiography (MeRGE) Heart Failure Collaborators
      • Doughty R.N.
      • Klein A.L.
      • Poppe K.K.
      • Gamble G.D.
      • Dini F.L.
      • et al.
      Independence of restrictive filling pattern and LV ejection fraction with mortality in heart failure.
      Several studies have shown RFP to be a strong predictor of LV remodeling and adverse clinical outcome, independent of age and LV ejection fraction (LVEF).
      • Meta-analysis Research Group in Echocardiography (MeRGE) Heart Failure Collaborators
      • Doughty R.N.
      • Klein A.L.
      • Poppe K.K.
      • Gamble G.D.
      • Dini F.L.
      • et al.
      Independence of restrictive filling pattern and LV ejection fraction with mortality in heart failure.
      In patients who undergo SVR, the RFP reversed to normal in patients with preserved RWT.
      • Fantini F.
      • Toso A.
      • Menicanti L.
      • Moroni F.
      • Castelvecchio S.
      Restrictive filling pattern in ischemic cardiomyopathy: insights after surgical ventricular restoration.
      Therefore, we designed this pilot study to study the association of preserved RWT on LV function and survival in patients with ICM receiving medical therapy. We hypothesized that this would help define responders to SVR.

      Methods

      This was a prospective study conducted in the Department of Cardiology at St John's Medical College Hospital, Bangalore, India, from December 2017 to January 2020. We enrolled 165 patients who presented to our department with congestive heart failure. All patients had a history of ST elevation/non-ST elevation myocardial infarction. The exclusion criteria were atrial fibrillation or other persistent cardiac rhythm alterations, ventricular paced rhythm, left bundle branch block, any mitral or aortic valve stenosis, previous valve repair or prosthetic valve implant, moderate-to-severe mitral regurgitation, need for valve surgery, cardiogenic shock or LV assist devices, and suboptimal echocardiographic examination. All patients underwent routine blood investigations and a baseline N-terminal pro B-type natriuretic peptide (NT pro-BNP). All patients were followed-up clinically until the end of study (24 months). All-cause mortality and readmissions for heart failure were analyzed.
      The study was approved by our institutional ethics committee (IEC Ref No. 22/2017 dated March 10, 2017) and all patients gave informed consent for being part of the study and for serial 2-dimensional echocardiograms and possible publication of data with ensured patient confidentiality.

       Echocardiographic Study

      Echocardiographic examination was done at baseline and at 6, 12, 18, and 24 months using a GE Vivid 7 machine (GE Healthcare, Chicago, Ill). We registered the averages of measurements of 3 cardiac cycles for each patient with echocardiographic monitoring. A standard 2-dimensional echocardiographic study was performed for assessment of LV wall thickness and dimensions according to the American Society of Echocardiography/European Association of Echocardiography recommendations.
      • Nagueh S.F.
      • Smiseth O.A.
      • Appleton C.P.
      • Byrd III, B.F.
      • Dokainish H.
      • Edvardsen T.
      • et al.
      ASE/EACVI Guidelines and Standards
      Recommendations for the Evaluation of left ventricular diastolic function by echocardiography: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging.
      Diastolic and systolic LV internal diameters were measured from the parasternal long-axis view. Septal wall thickness and posterior wall thickness were measured in end-diastole. The RWT was calculated as 2 × posterior wall thickness/LV diastolic diameter. EF was measured by Simpson's method.
      • Lang R.M.
      • Bierig M.
      • Devereux R.B.
      • Flachskampf F.A.
      • Foster E.
      • Pellikka P.A.
      • et al.
      Recommendations for chamber quantification: a report from the American Society of Echocardiography's guidelines and standards committee and the chamber quantification writing group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology.
      Systolic pulmonary artery pressure was calculated from the tricuspid regurgitation trace using continuous wave Doppler.
      • Lang R.M.
      • Bierig M.
      • Devereux R.B.
      • Flachskampf F.A.
      • Foster E.
      • Pellikka P.A.
      • et al.
      Recommendations for chamber quantification: a report from the American Society of Echocardiography's guidelines and standards committee and the chamber quantification writing group, developed in conjunction with the European Association of Echocardiography, a branch of the European Society of Cardiology.
      The entire sample was classified into 2 groups based on RWT (RWT ≥ 0.34 and RWT < 0.34).

       Diastolic Parameters

      Measures of the ratio of early mitral filling velocity/late filling velocity (E/A ratio), and E-velocity deceleration time were done on the pulsed-wave Doppler mitral-inflow profile.
      • Dini F.L.
      • Capozza P.
      • Donati F.
      • Simioniuc A.
      • Corciu A.I.
      • Fontanive P.
      • et al.
      Patterns of left ventricular remodeling in chronic heart failure: prevalence and prognostic implications.
      Tissue Doppler imaging was done by placing the sample volume at the side of the medial (septal e′) and lateral annulus (lateral e′)from the apical 4-chamber view.
      • Nagueh S.F.
      • Smiseth O.A.
      • Appleton C.P.
      • Byrd III, B.F.
      • Dokainish H.
      • Edvardsen T.
      • et al.
      ASE/EACVI Guidelines and Standards
      Recommendations for the Evaluation of left ventricular diastolic function by echocardiography: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging.
      Diastolic filling pattern was defined as restrictive with E/A ratio ≥ 2.
      • Nagueh S.F.
      • Smiseth O.A.
      • Appleton C.P.
      • Byrd III, B.F.
      • Dokainish H.
      • Edvardsen T.
      • et al.
      ASE/EACVI Guidelines and Standards
      Recommendations for the Evaluation of left ventricular diastolic function by echocardiography: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging.

       Statistical Analysis

      Categorical variables are presented as counts and percentages and compared using the χ2 test. The distribution of all continuous echocardiographic variables were examined using QQ plots and summarized as mean and standard deviation and compared between groups by independent samples t test. Survival time and time to readmission were compared between the RWT groups using Kaplan-Meir plots with 95% confidence interval and Log-rank test.
      The echocardiographic measures were compared between baseline, 6, 12, 18, and 24 months follow-up times using repeated measures analysis of variance. A P value < .05 was considered statistically significant. All analyses were carried out using STATA release 15 (StataCorp, College Station, Tex).

      Results

       Patient Population

      There were 118 men and the mean age of the study population was 58.28 ± 14.7 years. All patients had experienced a prior myocardial infarction (MI) (median time lapse from MI to present admission was 7.5 months). A majority had experienced an anterior wall MI (n = 84), whereas 7 patients experienced inferior wall MI. The remaining 74 patients experienced non-ST elevation MI. A majority were classified as having advanced stage heart disease (New York Heart Association [NYHA] functional class III or IV in 70% of cases). All patients were receiving maximally tolerated doses of antifailure medications, which included angiotensin converting enzyme inhibitors, angiotensin receptor inhibitors, loop diuretics, spironolactone, cardioselective beta blockers, dual antiplatelet agent, and statins; some patients were taking digoxin and those eligible were taking sacubitril. There were 120 (72.7%) patients with hypertension and 112 (67.8%) patients had diabetes mellitus. The baseline clinical parameters are listed in Table 1. The patients with preserved RWT (group 1; n = 117) had significantly more hypertension and diabetes. The patients with decreased RWT (group 2; n = 48) were in a significantly higher NYHA functional class and had significantly greater incidence of anterior wall MI (Table 1). The overall all-cause mortality in group 1 was 7 (5.9%) and in group 2 was 35 (72.9%) (P < .0001) (Figures 1 and 2). The NT pro-BNP at baseline was more significantly elevated in group 2 compared with group 1 (1200.5 ± 400 vs 2500.7 ± 346; P < .0001).
      Table 1Baseline clinical characteristics of patients
      Clinical characteristicRWT > 0.34

      (n = 117)
      RWT < 0.34

      (n = 48)
      P value
      Age62 ± 14.258.8 ± 6.8.736
      Male98 (84)20 (42).184
      Htn101 (86)19 (40)<.001
      DM89 (76)23 (48).008
      AWMI45 (38)39 (81)<.001
      IWMI6 (5)1 (2%).675
      NSTEMI52 (44)22 (46).999
      NYHA functional class2.98 ± 1.123.85 ± 2.1.0086
      Values are presented as mean ± standard deviation or n (%). RWT, Relative wall thickness; Htn, hypertension; DM, diabetes mellitus; AWMI, anterior wall myocardial infarction; IWMI, inferior wall myocardial infarction; NSTEMI, non-ST elevation myocardial infarction; NYHA, New York Heart Association.
      Figure thumbnail gr1
      Figure 1Kaplan-Meier survival plot of mortality for congestive heart failure. Two lines represent relative wall thickness (RWT) ≥ 0.34 and RWT < 0.34 groups. Shaded area represents the 95% confidence interval. The numbers at risk at the beginning of the follow-up time were n = 106 in RWT ≥ 0.34 group and n = 59 in RWT < 0.34 group. Mortality was 9 and 39 in the 2 groups, respectively. Log-rank test P < .001 for the comparison between the 2 RWT groups.
      Figure thumbnail gr2
      Figure 2Kaplan-Meier plot of readmission during the follow-up period. Two lines represent relative wall thickness (RWT) ≥ 0.34 and RWT < 0.34 groups. Shaded area represents the 95% confidence interval. The numbers at risk at the beginning of the follow-up time were n = 106 in RWT ≥ 0.34 group and n = 59 in RWT < 0.34 group. Readmissions were 31 and 58 in the 2 groups, respectively. Log-rank test P < .001 for the comparison between the 2 RWT groups.
      All patients were followed on an outpatient basis. The number of readmissions for heart failure in group1 was 31 (26.5%) and in group 2 was 58 (120.8%) (P < .0001). Information on patients who did not come for follow-up was procured by telephone for clinical update (death and/or hospitalizations). None of the patients underwent SVR, LV assist device, or heart transplant.

       Echocardiographic Data

      All patients showed an echocardiographic picture of typical ICM with severely reduced LVEF, increased LV end diastolic volume index, increased left atrial volume, high systolic pulmonary artery pressure (>40 mm Hg). They were divided into 2 groups based on RWT (Table 2). The left atrial volume was also higher in group 2. Severe LV diastolic dysfunction as defined by E/A and E/e′ was also higher in group 2. Out of 165 patients studied who fulfilled all inclusion criteria, 30 patients had RFP defined as E/A ≥ 2.
      Table 2Two-dimensional (2D) echocardiographic parameters of the 4 groups of ischemic cardiomyopathy patients
      2D studyRWT ≥ 0.34

      (n = 117)
      RWT < 0.34

      (n = 48)
      Intergroups comparison
      LVIDd (cms)4.96 ± 0.675.72 ± 0.67<.0001
      LVIDs (cms)3.66 ± 0.724.40 ± 0.86<.0001
      LVEF (%)38.37 ± 6.0335.27 ± 7.39<.0001
      PASP (mm Hg)35.42 ± 12.8035.22 ± 11.27<.0001
      LA (cms)3.82 ± 0.723.90 ± 0.53.0025
      E/A ratio0.96 ± 0.411.01 ± 0.39.0005
      E/e′ ratio11.19 ± 3.8012.13 ± 5.39.003
      DT (msec)152.44 ± 46.15159.02 ± 54.53.014
      PWDd (cms)1.088 ± 0.140.95 ± 0.18<.0001
      IVSd (cms)1.068 ± 0.200.92 ± 0.20.0002
      RWT (cms)0.43 ± 0.070.32 ± 0.089<.0001
      TAPSE1.96 ± 0.2981.89 ± 0.34.02
      RWT, Relative wall thickness; LVIDs, left ventricular diameter in diastole; LVIDs, left ventricular diameter in systole; LVEF, left ventricular ejection fraction; PASP, systolic pulmonary artery pressure; LA, left atrial; E/A, early mitral filling to late mitral filling velocity; E/e′, TDI e wave velocity; DT, deceleration time; PWDd, posterior wall diameter in diastole; IVSd, interventricular septal diameter in diastole; RFP, restrictive filling pattern; TAPSE, tricuspid annular motion in systole.
      When the entire cohort was analyzed, it was seen that patients with greater LV internal diameter end diastole (P < .0001), greater LV internal diameter end systole (P = .0009), greater left atrial volume (P = .02), RFP: E/A >2 (P = .02) had lesser RWT (P < .0001). Patients with ICM who presented with congestive heart failure, those who had thinner LV walls demonstrated by lower RWT (group 2) had increased mortality (median survival, 17 months; P < .0001) (Figure 1). These patients had a baseline geometric pattern of LV dilated remodeling, indicated by very low RWT and associated very high NT pro-BNP levels. The patients with preserved RWT (group 1) demonstrated a baseline eccentric remodeling and had lower mortality with associated lower NT pro-BNP levels. In our cohort, the RFP had no association with mortality The RFP did not correlate with RWT. The association of RFP could again be confounded by the small sample size of patients with RFP.

       Follow-up Echocardiographic Data

      The echocardiographic measures demonstrated LV dilatation, which was significant over time at 6, 12, 18, and 24 months in both groups (Table 3). There was further LV dilatation noted at follow-up, although the increase in LV dimensions was not significant. The diastolic dysfunction as measured by the E/A ratio remained almost the same in group 1 with preserved RWT, whereas in group 2 with decreased RWT it showed improvement at 24 months (Figure 3).
      Table 3Two-dimensional echocardiographic parameters of the 2 groups of ischemic cardiomyopathy patients at follow-up
      ParameterGroup6 mo

      (n = 141)
      12 mo

      (n = 123)
      18 mo

      (n = 118)
      24 mo

      (n = 117)
      Time × group interaction P value
      P value from repeated measures analysis of variance.
      LVIDd (cms)RWT ≥ 0.34

      RWT < 0.34
      4.96 ± 0.67

      5.92 ± 0.94
      5.72 ± 0.67

      6.18 ± 0.67
      5.34 ± 0.6

      6.0 ± 0.67
      5.37 ± 0.59

      6.11 ± 0.7
      .132
      LVIDs (cms)RWT ≥ 0.34

      RWT < 0.34
      3.66 ± 0.72

      4.74 ± 0.83
      4.40 ± 0.86

      4.98 ± 0.69
      3.97 ± 0.69

      4.92 ± 0.68
      3.97 ± 0.69

      4.9 ± 0.7
      .990
      LVEF (%)RWT ≥ 0.34

      RWT < 0.34
      38.37 ± 6.03

      31.45 ± 7.53
      35.27 ± 7.39

      31 ± 7.5
      36.1 ± 6.1

      31.4 ± 7.9
      36.6 ± 6.09

      31.4 ± 8.33
      .836
      LA (cms)RWT ≥ 0.34

      RWT< 0.34
      3.84 ± 0.7

      3.82 ± 0.72
      4.17 ± 3.4

      3.90 ± 0.53
      3.87 ± 0.62

      3.98 ± 0.42
      3.87 ± 0.62

      3.98 ± 0.44
      .921
      E/A ratioRWT ≥ 0.34

      RWT < 0.34
      0.96 ± 0.41

      1.19 ± 3.80
      1.01 ± 0.39

      1.13 ± 5.39
      1.19 ± 0.63

      1.24 ± 0.87
      1.19 ± 0.63

      1.26 ± 0.88
      <.001
      RWT (cms)RWT ≥ 0.34

      RWT < 0.34
      0.43 ± 0.07

      0.27 ± 0.072
      0.42 ± 0.008

      0.28 ± 0.011
      0.42 ± 0.08

      0.29 ± 0.05
      0.42 ± 0.08

      0.28 ± 0.06
      .9951
      Values are presented as mean ± standard deviation. LVIDd, Left ventricular diameter in diastole; RWT, relative wall thickness; LVIDs, left ventricular diameter in systole; LVEF, left ventricular ejection fraction; LA, left atrial; E/A ratio, early mitral filling to late mitral filling velocity.
      P value from repeated measures analysis of variance.
      Figure thumbnail gr3
      Figure 3Estimated average ratio of the early mitral filling velocity/late filling velocity (E/A) and 95% confidence interval at each follow-up time in the relative wall thickness (RWT) ≥ 0.34 and RWT < 0.34 groups.

      Discussion

      In a study of systolic heart failure, it was shown that eccentric LV remodeling defined as preserved RWT and patients with thinner LV posterior walls (lower RWT) had a relatively more dilated pattern of remodeling similar to dilated cardiomyopathy, when followed-up, had an independent and incremental risk of adverse outcome associated with decreased RWT.
      • Dini F.L.
      • Capozza P.
      • Donati F.
      • Simioniuc A.
      • Corciu A.I.
      • Fontanive P.
      • et al.
      Patterns of left ventricular remodeling in chronic heart failure: prevalence and prognostic implications.
      In our patients with ICM and systolic heart failure, patients with decreased RWT were in more advanced heart failure as assessed by NYHA functional class. These patients had significantly greater LV diameters and significantly lesser LVEF, demonstrating significantly greater systolic dysfunction than the patients with preserved RWT. This was also reflected by a greater level of baseline NT pro-BNP. The E/A ratio was greater in the patients with decreased RWT signifying greater diastolic dysfunction. The left atrial dimensions were also significantly greater, as was the deceleration time, which are indirect indicators of diastolic dysfunction.
      • Fantini F.
      • Toso A.
      • Menicanti L.
      • Moroni F.
      • Castelvecchio S.
      Restrictive filling pattern in ischemic cardiomyopathy: insights after surgical ventricular restoration.
      When followed over 24 months, there was a significantly higher all-cause mortality and significantly greater readmissions for heart failure in patients with decreased RWT. Elevated levels of BNP are strongly associated with outcomes, independent of therapy.
      • Feldman A.M.
      • Mann D.L.
      • She L.
      • Bristow M.R.
      • Maisel A.S.
      • McNamara D.M.
      • et al.
      Prognostic significance of biomarkers in predicting outcome in patients with coronary artery disease and left ventricular dysfunction.
      ,
      • Castelvecchio S.
      • Baryshnikova E.
      • Pina I.L.
      • Ambrogi F.
      • Milani V.
      • Tramarin R.
      • et al.
      Longitudinal profile of NT-proBNP levels in ischemic heart failure patients undergoing surgical ventricular reconstruction: the Biomarker Plus study.
      At 24 months of follow-up, there was an increase in LV dimensions in both groups, although not statistically significant (Table 3). But, the LV dimensions of group 2 remained significantly larger than group 1. The LVEF was also similarly lesser in group 2 at 24 months but was not significantly different from its baseline values. The diastolic function as measured by the E/A ratio did not vary at 24 months from baseline in group 1 and showed improvements in group 2 at 12 months onward. We had only 30 patients with RFP (E/A > 2). Because this sample size was small, we were not able to define the effect of RFP and diastolic dysfunction on clinical outcomes.
      All of these patients, while on maximally tolerated antiheart failure medications, had significantly higher all-cause mortality and readmissions for heart failure. SVR has shown benefit in patients with ICM and refractory heart failure.
      • Athanasuleas C.L.
      • Buckberg G.D.
      • Stanley A.W.
      • Siler W.
      • Dor V.
      • Di Donato M.
      • et al.
      Surgical ventricular restoration in the treatment of congestive heart failure due to post-infarction ventricular dilation.
      The LV volume tends to be only a weak determinant of clinical improvement because it has often been observed that patients with the same end diastolic volume, end systolic volume, and EF have diverging prognosis.
      • Pocar M.
      • Di Mauro A.
      • Passolunghi D.
      • Moneta A.
      • Alsheraei A.M.
      • Bregasi A.
      • et al.
      Predictors of adverse events after surgical ventricular restoration for advanced ischaemic cardiomyopathy.
      ,
      • Di Donato M.
      • Sabatier M.
      • Dor V.
      • Toso A.
      • Maioli M.
      • Fantini F.
      Akinetic versus dyskinetic postinfarction scar: relation to surgical outcome in patients undergoing endoventricular circular patch plasty repair.
      For the success of SVR, a discrete area of dyskinesis/akinesis with preserved contractile remote myocardium is a prerequisite.
      The main focus should be directed toward the nature of myocardial tissue that is left behind after scar excision during SVR (Video 1). The nature of the border zone myocardium and viability of the contractile myocardium needs to be ascertained before SVR.
      Figure thumbnail fx3
      Video 1Surgical technique of surgical ventricular restoration in a patient with ischemic cardiomyopathy and refractory heart failure using a rectangular intra ventricular patch. Video available at: https://www.jtcvs.org/article/S2666-2736(21)00051-6/fulltext.
      Analyzing survival based on the preoperative LV substrate in the largest registry on SVR the overall 5-year survival was 69%.
      • Athanasuleas C.L.
      • Buckberg G.D.
      • Stanley A.W.
      • Siler W.
      • Dor V.
      • Di Donato M.
      • et al.
      Surgical ventricular restoration in the treatment of congestive heart failure due to post-infarction ventricular dilation.
      In the subanalysis based on whether the area of infarct was akinetic or dyskinetic, the overall 5-year survival for dyskinesia was 80%, whereas for akinesia it was 65%. Although akinesia was present in 66% of cases, dyskinesia was seen in 34%. Among the ventricles with LV end-systolic volume index (ESVI) ≥80 mL/m2, akinesia was present in 73.3% and dyskinesia in 26.7%. When survival was analyzed based on the preoperative end-systolic volume index signifying LV dilatation, the patients with ESVI <80 mL/m2 had a 5-year survival of 80%, whereas patients with ESVI of 80 to 120 mL/m2 had a 5-year survival of 70%. The patients with ESVI ≥120 mL/m2 had the lowest 5-year survival at 64%. These findings lead us to infer that SVR in larger ventricles associated with an akinetic scar have a relatively worse prognosis than smaller ventricles with predominantly dyskinetic scars. However, earlier studies by Di Donato and colleagues
      • Di Donato M.
      • Sabatier M.
      • Dor V.
      • Toso A.
      • Maioli M.
      • Fantini F.
      Akinetic versus dyskinetic postinfarction scar: relation to surgical outcome in patients undergoing endoventricular circular patch plasty repair.
      have demonstrated that patients with a large akinetic LV aneurysm who had the most severely impaired preoperative cardiac function (largest ventricular volumes and highest mean pulmonary pressures) benefited from aneurysm repair as much as those with dyskinetic aneurysm.
      The eccentric LV remodeling with preserved RWT was shown to be beneficial following SVR.
      • Fantini F.
      • Toso A.
      • Menicanti L.
      • Moroni F.
      • Castelvecchio S.
      Restrictive filling pattern in ischemic cardiomyopathy: insights after surgical ventricular restoration.
      There were significant improvements in the RFP following SVR only in those patients with preserved RWT at baseline. The preservation of RWT can be considered a marker for contractile reserve in patients with LV aneurysms.
      Although the clinical benefits of SVR have been demonstrated in large registries, the STICH trial negated the beneficial effects of SVR when performed concomitantly with coronary artery bypass grafting (CABG).
      • Jones R.H.
      • Velazquez E.J.
      • Michler R.E.
      • Sopko G.
      • Oh J.K.
      • O'Connor C.M.
      • et al.
      Coronary bypass surgery with or without surgical ventricular reconstruction.
      There were several problems with the conduct of this study; 13% of patients enrolled in the STICH trial had no MI. Myocardial viability was investigated only in 267 patients (26.7%), among whom non-viable myocardium was present in 76 patients only (28.5%). Out of the 191 patients with viable myocardium, 99 underwent CABG plus SVR and 92% underwent CABG alone. Then, extrapolating the data, 37.1% (99 out of 237) of all patients had an inappropriate procedure.
      • Holly T.A.
      • Bonow R.O.
      • Arnold J.M.
      • Oh J.K.
      • Varadarajan P.
      • Pohost G.M.
      • et al.
      Myocardial viability and impact of surgical ventricular reconstruction on outcomes of patients with severe left ventricular dysfunction undergoing coronary artery bypass surgery: results of the Surgical Treatment for Ischemic Heart Failure trial.
      It is known that patients who had, during the postoperative period, a systolic volume <60 mL/m2 had a significantly lower 5-year mortality than patients where the systolic volume was ≥60 mL/m2 (9.8% vs 27.0%). Patients with postoperative volume reduction ≥30%, if compared with patients with volume reduction <30%, had a lower 5-year mortality (13.5% vs 22.1%). The 5-year mortality in CABG alone was 28%, even if not directly comparable to the previous data.
      • Michler R.E.
      • Rouleau J.L.
      • Al-Khalidi H.R.
      • Bonow R.O.
      • Pellikka P.A.
      • Pohost G.M.
      • et al.
      Insights from the STICH trial: change in left ventricular size after coronary artery bypass grafting with and without surgical ventricular reconstruction.
      These findings imply that a further analysis of the STICH trial found that, with a correct surgical technique and a good surgical indication, survival of patients who had CABG and SVR was definitively high and very likely better than survival of patients who had CABG alone.
      Therefore, extrapolating our findings of 2 years of medical treatment alone, we can hypothesize preserved RWT may benefit from SVR. SVR in reduced RWT may not have good outcomes because it may resurrect the Batista debacle.
      • Konstam M.A.
      • Kramer D.G.
      • Patel A.R.
      • Maron M.S.
      • Udelson J.E.
      Left ventricular remodeling in heart failure: current concepts in clinical significance and assessment.
      ,
      • Schinkel A.F.
      • Poldermans D.
      • Rizzello V.
      • Vanoverschelde J.L.
      • Elhendy A.
      • Boersma E.
      • et al.
      Why do patients with ischemic cardiomyopathy and a substantial amount of viable myocardium not always recover in function after revascularization?.

       Limitations

      This is a small sample size pilot study with a short follow-up period of 24 months. Longer follow-up may be required to determine factors affecting mortality. We also could not do the Cox proportional hazard model for mortality because the mortality numbers were too low. The lack of cardiac magnetic resonance data is also a limitation in investigating the relationship between RFP, RWT, ischemia, and replacement fibrosis. Another major limitation of our study is that we have studied the association of RWT on outcomes of heart failure in medically treated patients. We did not study patients who underwent SVR. The association of RWT on outcomes in patients who underwent SVR will be our next objective.

      Conclusions

      In this pilot study, patients with ICM who showed a preserved RWT indicative of eccentric LV remodeling were associated with decreased mortality (Figure 4). As was seen in previous studies, it can be hypothesized that the eccentric remodeling pattern in ICM may be a better substrate for SVR.
      Figure thumbnail gr4
      Figure 4Left ventricular function and survival in ischemic cardiomyopathy. Patients with preserved relative wall thickness (RWT) had lesser all-cause mortality and readmissions for heart failure.

       Conflict of Interest Statement

      The authors reported no conflicts of interest.
      The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling or reviewing manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest.

      Supplementary Data

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