Surgical therapy for dilated cardiomyopathy.

As the next millennium approaches, excitement and promise characterize the future of dilated cardiomyopathy. Until recently, dilated cardiomyopathy was considered an incurable, uniformly fatal chronic disease. Epidemiologic studies have demonstrated that at least a quarter of patients with recent onset of symptoms with cardiomyopathy manifest spontaneous improvement and a sustained favorable prognosis. It is imperative that patients who present with new-onset cardiomyopathy be managed medically and closely followed. Medical treatment remains the foundation of therapy, and certainly the advent of beta-blocker use may herald further benefit beyond that observed with conventional therapy (ACE inhibitors and digoxin). Unless mechanical support is required for hemodynamic instability and end organ failure, patients should be treated medically and observed. As discussed earlier, transient mechanical support as a bridge to recovery should be considered in the appropriate clinical scenario before committing to cardiac transplantation. Patients with established disease who have been followed for extended periods (> 6 months) that have progressive symptoms despite optimal medical therapy should be considered for surgical therapies. Cardiac transplantation is available to only a minority of the diseased population. All newer modalities of surgical unloading therapy theoretically reduce wall stress. Clearly in dilated cardiomyopathy, ventricular performance is reduced; however, individual myocyte contractile function may be intact. Studies of isolated myocytes (which are unloaded) have yielded conflicting data; however, if contractile function is intact and performance is reduced primarily secondary to abnormal loading conditions, surgical unloading therapies should yield benefit. Hence the thesis of Batista that geometric alteration will improve performance assumes intrinsic integrity of the myocyte contractile function. The implication of intrinsic myocyte contractile dysfunction is that surgical remodeling does not yield improved ventricular performance. Although clinicians have learned that selection criteria appear to play a role in predicting beneficial outcomes with cardiomyoplasty and the Batista procedure, clinical techniques to assess the integrity of myocyte function are unsophisticated. Quantifying interstitial fibrosis, assays for the degree of apoptosis, and various immunologic measures currently do not provide the insight necessary to predict outcomes reliably. The future assessment of dilated cardiomyopathy and the decision to consider alternative surgical procedures versus cardiac transplantation will likely be determined by biomolecular studies. At present, these new surgical procedures are promising therapies and potential alternatives to cardiac transplantation. Controlled studies to determine the clinical and survival benefit compared with medical therapy will ultimately be required, after the surgical techniques and patient selection criteria are refined. Randomized, prospective controlled studies assessing LVAD therapy and cardiomyoplasty are in progress.