Surgical treatment of heart failure: heart transplantation and ventricular restoration surgery
Area del Corazón, Complejo Hospitalario Universitario Juan Canalejo, Xubias, 84, La Coruña, 15006, Spain
* Corresponding author. Tel: +34 981 178304; fax: +34 981 178299. E-mail address: mcrelei{at}canalejo.org
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Heart transplantation (HT) is the only established surgical approach to the treatment of refractory heart failure. Survival after HT in Spain is 80% at 1 year, 70% at 5 years, and 60% at 10 years. The causes of death after HT depend on the time elapsed since transplant. In the first month, deaths are due mainly to acute allograft failure, between months 1 and 12 to infection and rejection, and thereafter to neoplasia, sudden cardiac arrest, or allograft vasculopathy. The main limitation on the application of HT to appropriately selected HF patients is the shortage of donors. Ventricular restoration surgery (VRS) comprises a set of surgical procedures for prevention of post-infarction ventricular remodelling. These techniques aim to reduce the volume and restoring the elliptical shape of the left ventricle by exclusion of the infarcted non-contracting segment. No randomized studies assessing the efficacy of VRS have yet been completed, and the results of the international multicentre trial STICH, in which patients with ischaemic cardiomyopathy are randomized to medical therapy, coronary bypass alone, or coronary bypass with VRS, are eagerly awaited. However, data from a large registry of patients with VRS show good results, with an overall 30-day mortality of 5.3% and a 5-year survival rate of 68%.
Key Words: Heart transplantation • Ventricular restoration surgery
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Surgical treatment of heart failure: heart transplantation and ventricular restoration surgery |
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Heart transplantation
Heart transplantation (HT) is an irreversible surgical procedure in which a damaged heart is removed and replaced with a healthy donor heart. It requires long-term follow-up and immunosuppressive therapy, is expensive, and is dependent on the availability of donated hearts, which are scarce. However, it is currently the only established surgical approach to the treatment of Stage D (refractory) heart failure (HF).1 Although controlled trials have never been conducted, it is considered that in comparison with conventional treatment it significantly increases survival, exercise capacity, return to work and quality of life, always provided that patients meet proper selection criteria (Recommendation Class I, Evidence Level C of the European Society of Cardiology guidelines).2 According to data from the Registry of the International Society for Heart and Lung Transplantation (ISHLT),3 more than 70 000 heart transplants have been performed worldwide, with overall survival rates of more than 80% after 1 year and 50% after 10 years, an absolute half-life of 9.6 years, and a half-life of 12 years conditional on survival for 1-year post-transplantation. Given that in the REMATCH trial4 less than 23% of Stage D HF patients with contraindications for HT survived for 2 years or more, there is little doubt about the benefits of HT. Furthermore, survival rates are improving,1 and ISHLT Registry data3 show that more than 90% of survivors have no activity limitations. Although alternative surgical therapies are currently being developed,5 their role in the management of HF remains to be defined.
According to the latest AHA/ACC guidelines, the indications for HT are those listed in Table 1. The main indication is refractory HF, i.e. HF that has led to cardiogenic shock or dependence on intravenous inotropic agents. Less common indications include recurrent life-threatening arrhythmias or angina that are refractory to all currently available treatments. The HT recipient selection process must (i) confirm the severity of HF to rule out the application of other therapies [medical treatment, coronary revascularization, valve replacement, or ventricular restoration surgery (VRS)], (ii) rule out contraindications, and (iii) determine prognosis.6 Heart transplantation is contraindicated in the presence of any condition that increases the risk of post-HT death, including advanced age, severe peripheral or cerebrovascular disease, irreversible dysfunction of kidney, liver, or lung (except where multiorgan transplantation is a possibility), cancer (whether present or past, if recurrence is likely), inability to comply with a complex medical regimen, irreversible pulmonary hypertension, or active systemic infection.
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In spite of the proven benefits of HT, the number of HT operations continues to fall3 because of lack of donors. Last year HT was available for fewer than 2500 patients in the USA,3 and for proportionally fewer still (less than 300) in Spain.7
HT in Spain: recent trends
The Spanish Heart Transplant Registry (SHTR)7 monitors all HTs performed in Spain since 1984, 4,680 as of December 2004. According to its records, survival after HT in Spain is 80% at 1 year, 70% at 5 years, and 60% at 10 years, the post-HT half-life being 13 years. The most frequent aetiology of the cardiopathy motivating HT is ischaemic heart disease, followed by dilated cardiomyopathy; these two conditions together account for 76% of HTs. They are followed by valve disease, which accounts for 9%. The death rate in the waiting list is 9%, or 16% if one includes patients removed from the waiting list before HT due to deterioration or other causes.
In recent years, the characteristics of donors and recipients have been changing, both groups showing an increase in mean age and in the prevalence of risk factors for post-HT morbimortality. A greater proportion of donor deaths are now due to stroke, and a greater proportion of recipients now have co-morbidities or have had previous cardiac surgery or anticoagulant treatment. Due to the donor shortage noted above, mean time on the waiting list has increased from 46 days in 1993 to 111 days in 2004, and a larger proportion of patients have urgent need of HT: in 2004, 35% of HTs were performed as urgent procedures.
The causes of death after HT depend on the time elapsed since transplant. In the first month, deaths are due mainly to acute allograft failure, between months 1 and 12 to infection and rejection and thereafter to neoplasia, sudden cardiac arrest, or allograft vasculopathy.
The trend in post-HT survival in Spain and changes in donor and recipient characteristics are brought out by analysis of SHTR records8 for three successive 5-year periods: 1990–1994, 1995–1999, and 2000–2004. The salient characteristics of recipients and donors in these periods are summarized in Table 2, whereas Figure 1 shows that in spite of the progressive decline in donor and recipient characteristics, the 1-year survival rate has progressively increased from 69–74% to 85% (P<0.0001) and the 5-year rate from 58–64% to 72% (P<0.0001). This improvement in prognosis is probably due to improvements in both immunosuppressive therapy and in expertise.
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Ventricular restoration surgery
The most frequent cause of HF is post-infarction ischaemic heart disease. Even with early revascularization, there is a subset of patients whom myocardial infarction leaves with ventricular shape and function abnormalities that increase their risk of further ischaemic events and of death. The transition from occluded vessel to scar to dilatation results in a remodelled ventricle.
The basic science underlying the novel technique of VRS is the recently improved understanding of normal cardiac structure and of how it is altered in the dilated failing heart. Post-infarct ventricular remodelling is an adaptive alteration in which the shape of the left ventricle, normally elliptical, becomes dilated and spherical.9 By Laplace's law, the enlargement of the chamber diameter implies an increase in the wall tension required for a given intraventricular pressure, and this in turn results in increased oxygen consumption, reduced subendocardial blood flow, and reduced systolic shortening. Furthermore, as the enlarging ventricle changes shape, the orientation of ventricular myofibrils becomes increasingly transverse rather than oblique, so that even the normal 15% shortening would generate a global ejection fraction (EF) of only 30%, instead of the 60% EF of elliptical ventricles with normal myofibril orientation.10,11
VRS comprises a set of surgical procedures aimed at reducing the volume and restoring the elliptical shape of the left ventricle by exclusion of the infarcted non-contracting segment. Following incision of the latter, the chamber is closed by suturing together the surrounding functional tissue, with or without an endoventricular patch. The history of these procedures goes back to Cooley et al.'s excision of a thin-walled aneurysm with direct closure,12 an operation that is now rarely pertinent, because early reperfusion saves the epicardial muscle that lies over the infarcted tissue, giving rise to a thick-walled akinetic region rather than a thin-walled dyskinetic one. Vincent Dor,13 recognizing that the adverse effects of akinesia on the remote non-infarcted myocardium are similar to those of dyskinesia, began to use endocardial patch plasty for both. VRS procedures now include operations variously denominated endoventricular circular patch plasty repair, the Dor procedure, left ventricular (LV) restoration, LV reconstruction,14 LV infarct exclusion surgery, LV aneurismectomy reconstruction,13 and surgical anterior ventricular endocardial restoration.15 However, VRS must be distinguished from partial left ventriculectomy (the Batista procedure), in which functional lateral wall tissue is resected and discarded. This latter technique has not lived up to initial expectations14,16 and is currently not considered useful for treatment of HF.1
Procedures performed concomitantly with VRS include coronary bypass and, when indicated, mitral valve repair.5,17 The targets of surgical treatment of HF can thus now be summarized as the three V's: vessel, valve, and ventricle.
Crucial to the success of VRS is precise identification of non-contractile (asynergic) tissue. The rule of thumb is that, after myocardial infarction, a segment in which 50% of the muscle tissue is necrotic will not regain contractile function after reperfusion, and the technique of choice for evaluation of the extent of necrosis is magnetic resonance imaging, which also allows evaluation of remote muscle function and LV end-systolic volume index (LVESVI).11
No randomized studies assessing the efficacy of VRS have yet been completed, and the results of the international multicentre trial STICH, in which patients with ischaemic cardiomyopathy are randomized to medical therapy, coronary bypass alone, or coronary bypass with VRS,18,19 are therefore awaited with considerable expectation. In the meantime, the main source of information is the RESTORE group, a team of cardiologists and surgeons working in 12 centres in the USA, Europe, South America, and Asia who have established a registry of their VRS patients and have begun to issue reports on their experience.9,20 The criteria for inclusion in this registry are prior anterior myocardial infarction, significant preoperative ventricular dilatation (LVESVI
60 mL/m2), and performance of VRS (with or without coronary bypass or mitral repair) on a non-contractile region occupying35% of the preoperative LV wall area. The latest RESTORE report5 concerns 1198 patients operated on between 1998 and 2003. VRS was accompanied by coronary bypass in 95% of these cases, by mitral valve repair in 22%, and by mitral valve replacement in 1%. Overall, 30-day mortality was 5.3% and 5-year survival was 68%. Logistic regression analysis identified an EF
30%, an LVESVI80 mL/m2, advanced New York Heart Association functional class and age 75 years as risk factors for death. It must be pointed out that RESTORE findings suffer not only from non-randomization of patients, but also from non-standardization of end-point criteria, drug regimens, and the measurement of EF and LV end-systolic volume. The other main source of evaluative information on VRS is a retrospective observational review of 1174 consecutive patients referred for HT at the Cleveland Clinic Foundation.14 Fewer than one fifth of these patients received transplants, and of the 200 who were considered for non-transplant surgery (17%), 47% underwent VRS. The 3-year survival rate of VRS patients was similar to that of HT patients, 86%. In view of the limited supply of donated hearts, it would seem that VRS must be considered as a valid alternative to HT in centres with the appropriate expertise.
Conflict of interest: none declared.
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