Benefits of Surgery in Obstructive Hypertrophic Cardiomyopathy: Bring Septal Myectomy Back for European Patients

Bring Septal Myectomy Back for European Patients

Barry J. Maron; Magdi Yacoub; Joseph A. Dearani

Disclosures

Eur Heart J. 2011;32(9):1055-1058. 

In This Article

The Case for Surgery

Certainly, the major advantage of a percutaneous catheter-based technique such as ASA is obvious—i.e. that it is not a surgical procedure, and therefore avoids a large measure of patient discomfort and inconvenience created by sternotomy, cardiopulmonary bypass, and 6 weeks of postoperative convalescence. However, the case for surgical myectomy as the preferred and most effective treatment option in adults and children with both LV outflow obstruction and severe drug-refractory symptoms is based on considerable short- and long-term evidence and the experience of numerous surgical centres throughout the world over almost five decades.[1–3,12–22,29–39]

Procedural Risk

In its early years, septal myectomy was accompanied by a relatively high ≥5% operative mortality.[3] However, over the last 15 years, with improved myocardial preservation and operative technique, myectomy has become a low-risk open-heart procedure (at the most experienced centres) associated with a markedly reduced operative mortality of <1% and now approaching zero.[3,13–22,35] This very low operative risk is most pertinent to those patients currently contemplating a septal reduction intervention, rather than the obsolete and irrelevant data from the very early surgical experience.[3,12,23–26]

Contemporary data therefore dispel the often misrepresented notion that myectomy is a risk-prone strategy because it is surgery, and alternately that alcohol ablation is safe simply because it is percutaneous. Indeed, the case can be made at this time that myectomy performed in experienced centres actually incurs the same or less procedural risk than ASA undertaken in unselected cardiac catheterization laboratories.[3,20,32,33] Although ASA is not an entirely benign strategy, we would nevertheless expect that procedural morbidity and mortality rates will decrease with time and operator experience as they have with myectomy. Nevertheless, it remains customary and prudent for myectomy to be performed by surgeons who have specific experience with this operation, given the important technical issues raised by the complex LV outflow tract anatomy characteristic of this disease and the limited visual exposure provided by the conventional transaortic approach.

Heart Failure and Quality of Life Benefit

In HCM, heart failure symptoms (i.e. exertional dyspnoea with or without chest pain) and outflow obstruction, due to mitral valve systolic anterior motion (SAM), are potentially reversible.[1–3] Indeed, the myectomy procedure consisting of resection of a small amount of basal septal muscle with consequent enlargement of the LV outflow tract[37] results in permanent abolition of mechanical impedance to LV outflow and SAM-related mitral regurgitation, and normalization of LV pressures.[1–3,12–22,29–38] As a consequence, in the vast majority of such patients, disabling heart failure symptoms are relieved with restoration of normal exercise capacity and quality of life.[1–3,12–22,29–38]

Specifically, post-operative longitudinal studies show sustained clinical improvement with 85–90% of patients becoming asymptomatic (or only mildly symptomatic), an average of 8 years (and up to 25 years) after myectomy.[13–17,20] Although myectomy and ASA both produce haemodynamic and symptomatic benefit, some comparative observational and non-randomized studies[3,17,20,32–36] and one recent meta-analysis[40] show that surgery can provide the most consistent, complete, and rapid relief of symptoms (particularly in patients <65 years of age) and is associated with lower post-intervention outflow gradients and fewer procedural complications and reinterventions.

Survival Benefit

Notably, in addition to the well-acknowledged improvement in quality of life, there is also evidence that myectomy favourably alters the natural course of HCM, improves long-term survival, and provides a reasonable expectation for normal or near-normal life expectancy.[15] In the large Mayo Clinic series,[15] operated patients experienced longevity similar to that expected in the general population, and superior to non-operated patients with outflow obstruction. After myectomy, survival free from all-cause mortality was 98, 96, and 83% at 1, 5, and 10 years; survival free from HCM-related mortality (heart failure and sudden death) was 99, 98, and 95%. This survival benefit is due to the normalization of LV pressure, and possible reduced arrhythmogenicity of the myocardial substrate and sudden death risk.[15,39] Because ASA is a much more recently introduced treatment modality, its truly long-term effects and outcome will remain unknown for many years.

Important Technical Advantages of Surgery

In ASA, precise targeting of basal septal muscle may be constrained by morphology of the vascular bed and specifically the size, distribution, and accessibility of septal perforator arteries.[41] In contrast, the myectomy surgeon has the distinct advantage of direct visualization of complex LV outflow tract anatomy which in turn permits recognition (and revision) of all structural abnormalities that contribute to mechanical subaortic obstruction in this notoriously heterogeneous phenotype.[2,42–50]

Left ventricular outflow tract structural variability may involve irregular distribution of septal thickness, anomalies of the mitral apparatus (and submitral structures) including direct insertion of the anterolateral papillary muscle into anterior mitral leaflet, and accessory papillary muscles producing mid-cavity muscular obstruction, as well as greatly elongated mitral valve leaflets.[2,3,42–50] Indeed, concern that the mitral valve leaflets can produce dynamic outflow obstruction, even after standard septal muscular resection, has led several surgeons to supplement myectomy with mitral valve repair or leaflet plication in selected patients[45–47] and to perform a more extensive and broader muscular resection than the classic Morrow procedure[12,37]—i.e. 'the extended myectomy' to mid-ventricular level and with reconstruction of subvalvular structures.[13,17,42,48,49] Therefore, as emphasized by Sigwart,[4] not all patients who may preferentially favour ASA (or have only access to ASA) are optimal candidates for this percutaneous septal reduction intervention on an anatomic basis.

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.

processing....