Since the early 1960s, surgical septal reduction, also known as septal myectomy, has been used as a therapy for the treatment of obstructive hypertrophic cardiomyopathy. Pioneered at the National Institute of Health by cardiac surgeon Dr. Glenn Morrow, himself a HCM patient, septal myectomy has become a mainstay of the HCM treatment arsenal.
For many years, the indications for ASA procedures has been limited to older patients with obstructive HCM who were not otherwise healthy enough to undergo open heart surgery. However, some doctors are now advocating to expand the indications for ASA to include symptomatic younger patients.
(For more information about myectomy and ASA, click here and scroll to bottom of page).
Current Guidelines for ASA
Current guidelines for HCM treatment, published in 2011 by the American College of Cardiology Foundation (ACC) and American Heart Association, recommend that ASA be reserved for older patients and for those who are not otherwise healthy enough to undergo septal myectomy. They consider open heart septal myectomy surgery to be the preferred method for septal reduction.
These guidelines assign a “Class III: Harm” designation (suggesting that the risks outweigh the benefit) and state that “alcohol septal ablation should not be done in patients with HCM who are less than 21 years of age and is discouraged in adults less than40 years of age if myectomy is a viable option.”
The European Society of Cardiology (ESC) guidelines, propagated in 2014, state that “septal ablation is controversial in children, adolescents and young adults because there is no long-term data on the late-effects of the myocardial scar in these groups, and because the technical difficulties and potential hazards of the procedure in smaller children and infants are greater.”
Recent Netherlands Study on ASA
Additionally, the researchers found that long-term survival following ASA was similar to survival rates for age-matched non-obstructive HCM patients who had not undergone ASA.
The study followed 217 HCM patients who underwent ASA because of symptomatic left ventricular outflow tract obstruction. The patients were divided into two groups: a younger group consisting of patients younger than 55, and an older group consisting of patients older than 55. Both groups were matched to equal sized control groups of non-obstructive HCM patients.
Over a total follow up period up to 12.2 years, the researchers found that patients under the age of 55 had a total 5-year survival of 94.9%, while their total 10-year survival was 90.2%. 5% of the younger patients experiencing A/V block, thus requiring permanent pacemakers. Patients over 55 had a total 5-year survival of 93.2%, while their total 10-year survival was 81.9%, with 13% experiencing A/V block and requiring a permanent pacemaker. The survival percentages were similar to those of the age-matched non-obstructive control groups.
Deciding on the Right Septal Reduction Method
In accordance with both the ACC and ESC guidelines, the researchers recommend that:
“all patients considered for septal reduction therapy [be] assessed by a multidisciplinary heart team (consisting of at least 1 cardiothoracic surgeon, an interventional cardiologist, and a cardiologist specialized in the care of patients with HCM) to determine the optimal therapy by taking into account not only age, but also factors such as mitral valve anatomy, coronary anatomy, septal thickness, and comorbidities. When both procedures are possible, shared decision making between the informed patient and treating physician should also be part of the equation. Furthermore, septal reduction therapy should be performed by experienced operators and confined to centers with substantial and specific expertise in HCM care.”
Should the Indications for ASA be Expanded?
In an article published in MedPage Today, the authors of this study propose that the indications for ASA be broadened to include younger patients.
“Because the improvement in functional status following alcohol septal ablation in young and elderly patients is similarly good, we propose that the indication for alcohol septal ablation can be broadened to younger patients,” Liebregts’ group suggested. “In other words, younger age alone should not be a reason to exclude alcohol septal ablation.“
According to Dr. Fifer, as centers have gained more long-term experience with ASA, the amount of ethanol alcohol injected into the heart has been reduced. This may be a factor impacting the findings of the current study, since increased mortality has been associated with higher dosages of ethanol. Therefore, Dr. Fifer urged caution of using ASA to treat patients with greater septal thicknesses which may require higher dosages of ethanol, as well as potential pacemaker implantation.
Nevertheless, Dr. Fifer thinks that the indications for ASA should be increased. “The present study provides the most robust data to date regarding the outcomes of ASA in younger patients, precisely the type of data that were missing at the time of writing of the ACCF/AHA and European Society of Cardiology guidelines.”
In addition, Fifer observed that opening up the indications for ASA would increase patient access to successful treatment, noting that there is limited availability of experienced surgical centers offering myectomy.
Experience of Treatment Team
Dr. Mackram Eleid and Dr. Rick Nishimura of the Mayo Clinic also filed an additional editorial comment, stating that “growing evidence supports that alcohol septal ablation is not fraught with the high risk that had been suspected and that long-term survival after alcohol septal ablation may be comparable to that of myectomy, potentially opening this treatment modality to a younger population as well as to center that do not have the surgical expertise,”
However, Eleid and Nishimura cautioned that “growing evidence supports that ASA is not fraught with the high risk that had been suspected and that long-term survival after ASA may be comparable to that of myectomy, potentially opening this treatment modality to a younger population as well as to centers that do not have the surgical expertise. It must be remembered that, as with any interventional technique, outcomes are highly dependent upon the knowledge and experience of the operators, and the excellent results in this study may not necessarily be extrapolated to all other centers.”