Asian Cardiovasc Thorac Ann 2008;16:269-271
© 2008 Asia Publishing EXchange Ltd
Surgical Ventricular Restoration and the STICH Trial
Marisa Di Donato, MD,
Lorenzo Menicanti, MD,
Hisayoshi Suma, MD1
Italy
1 Japan
Chronic ischemic heart failure has become a major public health problem in the western world, partly due to an aged population and more effective treatment of acute myocardial infarction (MI).1 Despite significant improvements in medical management, patients with ischemic heart failure are repeatedly readmitted for hospital care, and the majority will die within 3 years of diagnosis.2 Chronic ischemic cardiomyopathy is the negative result of so-called ventricular remodeling, characterized by a left ventricular (LV) volume increase and abnormal geometry, and frequently associated with mitral regurgitation.3 The concept of reducing wall stress through surgical restoration of LV cavity size and geometry is the guiding principle behind many innovative techniques aimed at improving heart failure of ischemic and nonischemic origin. Heart transplantation remains the treatment of choice for dilated cardiomyopathy, although in ischemic patients, operative risk is higher and survival lower than in those with nonischemic cardiomyopathy. Thus restoring myocardial perfusion (vessel), eliminating valvular regurgitation (valve), and restoring ventricular geometry (ventricle) has emerged as the first-line surgical approach (3V approach) to heart failure, because it can be performed in a single operation.4 Results of LV reconstruction have been favorable and consistent among groups, regardless of whether endoventricular circular patch plasty or a modified linear patch closure technique is used.5,6 Significant reductions in LV end-systolic volume index and improvements in ejection fraction, New York Heart Association class, and long-term survival have resulted. This surgical treatment, when combined with optimal medical management of heart failure, may now be as safe and effective as transplantation. Therefore, these modalities now form the first-line surgical therapy for heart failure, when applicable.7
Left ventricular aneurysm was first described in the 18th century, but it was not until 1935 when paradoxical motion in acutely ischemic myocardium was demonstrated that the physiologic implications of ventricular injury became apparent. Since then, the term aneurysm is more often used to describe dyskinesia of a particular region that expands in systole. In fact, LV aneurysm can be dyskinetic or akinetic, when myocardial fibrosis, calcification within the scar, and mural thrombosis tend to rigidify the aneurysm. Left ventricular aneurysm has also been described as a systolic-diastolic deformation with paradoxic expansion, or simply as diastolic deformation of the chamber. When the infarction is treated by early revascularization and the subepicardium is salvaged, the scar remains confined to the subendocardium; in this condition, the myocardial lesion is more often akinetic, and this type of regional asynergy is nowadays more frequently observed. Previously, in a large series of patients who underwent the Dor procedure, also termed surgical ventricular restoration (SVR), we demonstrated that outcome was more strictly linked to the extent rather than the type of LV asynergy (akinesia vs. dyskinesia), and that SVR is applicable also to a large akinetic ventricle without a discrete LV aneurysm.8 We recently reported our overall experience with SVR, and the clinical status and cardiac function in 1,161 patients with previous anterior MI who underwent SVR for symptoms of heart failure, angina, or both.9 Significant improvements in clinical status, cardiac function, and survival were observed. Figure 1
shows the updated survival rate in our study population.
View larger version (33K):
[in this window]
[in a new window]
|
Figure 1. Ten-year Kaplan-Meier survival curve in 1,161 patients with previous anterior myocardial infarction who underwent surgical ventricular restoration.
|
|
More recently, we described 3 types of abnormal LV shape after MI, which can be treated by SVR; we think that the form rather than the type of asynergy should guide the indication for this kind of surgery, and we should make an effort to create uniform definitions of shape (Figure 2). For example, after an anterior MI, LV shape elongates and widens at the equatorial diameter in a proportional way, so that the sphericity index (short-to-long axis ratio)-SI- does not change. Alternatively, the LV chamber may enlarge more at the equator, thus becoming spherical, and functional mitral regurgitation occurs. The conicity index –CI-, indicating the conical shape of the apex (normal value in diastole, 0.60 ± 0.09), can be markedly increased in the discrete aneurysm where the apical axis is larger than the equatorial diameter; in this case, conicity index is high but sphericity index is normal, while in LV dilation without a discrete aneurysm, conicity index is low but sphericity index is high. These changes in LV geometry represent the basis for heart failure progression (biomechanical model of heart failure), and the great challenge is to apply a therapeutic strategy that may improve both LV function and shape by reverting, arresting, or at least delaying the adverse remodeling process.
View larger version (45K):
[in this window]
[in a new window]
|
Figure 2. Echocardiography in 2-chamber view of 3 patients with post-infarction dilated cardiomyopathy. Each has a dilated ventricle and severely depressed pump function, but their left ventricular shapes are completely different.
|
|
The ongoing STICH trial (Surgical Treatment of Ischemic Heart failure)10 is an international randomized controlled clinical trial testing 2 primary hypotheses. The first is that coronary artery bypass grafting (CABG) confers long-term benefits in terms of mortality, morbidity, quality of life, and cost, over state-of-the art medical therapy in patients with depressed ejection fraction (
35%) and coronary vessels amenable for grafting. Hypothesis 2 is that surgical optimization of LV shape and size by SVR combined with CABG improves survival, free of hospitalization, morbidity and quality of life vs. CABG alone. To date, enrollment is complete for studies of both hypotheses, and nearly 2,000 patients have been enrolled at 96 centers in 25 countries. The primary outcome of the study on the 2nd hypothesis is expected in 2009, and data regarding the 1st hypothesis are expected in 2011. The need for this randomized trial for both hypotheses arises from the fact that data on the superiority of surgery over medical therapy are old and were obtained in small series from the CASS study that analyzed very few patients with a depressed ejection fraction, and also that the results of adding SVR to CABG, although promising, are observational and need to be validated.4–6,8,9,11
An important concept that the STICH trial will address is the potential functional recovery of remote unscarred regions after the scar is excluded by SVR (wall tension reduction), and we will learn by means of magnetic resonance imaging, ventriculography, echocardiography, and nuclear medicine studies of remote regions whether there is sufficient compensatory muscle to resume function. As for the primary hypothesis of restoration, the trial will definitively demonstrate whether the reduction of LV volume by SVR and surgical exclusion of the scar with concomitant CABG will add benefit to patients with dilated ischemic cardiomyopathy and heart failure.
If both primary hypotheses of the STICH trial will be confirmed, and surgical therapy proves to be superior to medical therapy, early aggressive evaluation of coronary artery disease as a potentially correctable etiology of new onset heart failure would be the preferred strategy. This could tremendously change the treatment of ischemic heart disease. Confirming the STICH revascularization hypothesis will dramatically increase the use of CABG in the many patients now being medically treated without evaluation for ischemic etiology. Confirming the 2nd hypothesis (the superiority of adding SVR to CABG), will mean SVR becomes a common, safe, and effective treatment strategy for ischemic heart failure. SVR is not a standardized procedure and different surgeons will perform different procedures in the STICH population; we hope that the trial will focus also on the role of surgeon experience and of technical differences, to avoid biased results.
REFERENCES
- Califf RM, Adams KF, McKenna WJ, Gheorghiade M, Uretsky BF, McNulty SE, et al. A randomized controlled trial of epoprostenol therapy for severe congestive heart failure: the Flolan International Randomized Survival Trial (FIRST). Am Heart J 1997;134: 44–54.[Medline]
- Tavazzi L. Epidemiology of dilated cardiomyopathy: a still undetermined entity. Eur Heart J 1997;18:4–6.[Free Full Text]
- Mann DL, Bristow MR. Mechanisms and models in heart failure: the biochemical model and beyond (Review). Circulation 2005;111: 2837–49.[Free Full Text]
- Athanasuleas CL, Buckberg GD, Stanley AW, 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. J Am Coll Cardiol 2004;44:1439–45.[Abstract/Free Full Text]
- Dor V, Sabatier M, Di Donato M, Maioli M, Toso A, Montiglio F. Late hemodynamic results after left ventricular patch repair associated with coronary grafting in patients with postinfarction akinetic or dyskinetic aneurysm of the left ventricle. J Thorac Cardiovasc Surg 1995;110:1291–301.[Abstract/Free Full Text]
- Menicanti L, Di Donato M. The Dor procedure: what has changed after fifteen years of clinical practice? J Thorac Cardiovasc Surg 2002;124:886–90.[Free Full Text]
- Spoor MT, Bolling SF. Nontransplant surgical options for heart failure. In: Cohn LH, Edmunds LH Jr, eds. Cardiac Surgery in the Adult. New York: McGraw-Hill, 2003:1639–48.
- 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. J Am Coll Cardiol 1997;29:1569–75.[Abstract]
- Menicanti l, Castelvecchio S, Ranucci M, Frigiola A, Santambrogio C, De Vincentiis C, et al. Surgical therapy for ischemic heart failure: single-center experience with surgical anterior ventricular restoration. J Thorac Cardiovasc Surg 2007;134:433–41.[Abstract/Free Full Text]
- Velazquez EJ, Lee KL, O’Connor CM, et al. The rationale and design of the Surgical Treatment for Ischemic Heart Failure (STICH) trial. J Thorac Cardiovasc Surg 2007;134:1540–47.[Abstract/Free Full Text]
- Killip T, Passamani E, Davis K. Coronary artery surgery study (CASS): a randomized trial of coronary bypass surgery. Eight years follow-up and survival in patients with reduced ejection fraction. Circulation 1985;72(Suppl V):102–9.
