Septal myectomy tied to lower long-term mortality vs. alcohol ablation for obstructive HCM
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Alcohol septal ablation for obstructive hypertrophic cardiomyopathy was associated with greater rate of 10-year all-cause death compared with septal myectomy, researchers reported.
According to data published in the Journal of the American College of Cardiology, adjustment for comorbidities failed to attenuate the elevated long-term mortality risk tied to alcohol septal ablation for obstructive hypertrophic cardiomyopathy (HCM) compared with myectomy.
“Over the past 2 decades, there has been an ongoing debate regarding the relative merits of septal myectomy vs. alcohol septal ablation for obstructive HCM, but there are few studies that directly compare the outcomes of the two procedures,” Hao Cui, MD, cardiovascular surgeon at Mayo Clinic, and colleagues wrote. “Furthermore, randomized trials of septal reduction therapy are unlikely to be undertaken in the near future, and actionable results regarding patient survival will require lengthy follow-up.”
To better understand the late outcomes of alcohol septal ablation (15.2%) compared with myectomy (84.8%) for obstructive HCM, researchers evaluated 3,859 patients who received treatment at three specialized HCM centers. The primary endpoint was all-cause mortality.
Researchers noted that individuals with obstructive HCM who underwent alcohol septal ablation were older (median age, 63 vs. 53.7 years; P < .001) and had smaller septal thickness (19 vs. 20 mm; P = .007) compared with those who underwent septal myectomy; the alcohol septal ablation group also had greater prevalence of renal failure, diabetes, hypertension and CAD.
Alcohol septal ablation vs. myectomy
There were four premature deaths in the alcohol septal ablation group and nine in the myectomy group, according to the study.
During a median follow-up of more than 6 years, the estimated 10-year rate of all-cause mortality was 26.1% in the patients who underwent alcohol septal ablation and 8.2% in those who underwent myectomy, and after adjustment for age, sex and comorbidities, mortality remained higher after alcohol ablation compared with myectomy (HR = 1.68; 95% CI, 1.29-2.19; P < .001).
“The choice of alcohol septal ablation or septal myectomy for septal reduction therapy involves many factors, including operator expertise with both approaches,” the researchers wrote. “Indeed, the latest practice guidelines encourage referral to comprehensive HCM centers if either of the procedures is unavailable. It is generally accepted that septal myectomy provides more immediate and complete relief of left ventricular outflow tract gradients and symptoms compared to alcohol septal ablation, but procedural risks are similar with the two methods, and recovery is more rapid with alcohol septal ablation.
“Despite the overall difference in long-term survival following alcohol septal ablation and surgical myectomy, selection of the method of septal reduction therapy should be individualized,” the researchers wrote. “The conclusion from the present study may not apply to those who have unusual morbidities such as cancer or systemic illnesses, which increase the risk of open heart surgery. Selection of septal reduction therapy method is best made after comprehensive evaluation at experienced HCM centers and detailed discussion between the patient and physicians.”
Who remains eligible for alcohol ablation
In a related editorial, Mark V. Sherrid, MD, director of the hypertrophic cardiomyopathy program at NYU Langone Health, and colleagues discussed how these findings relate to clinical practice as well as the future of septal myectomy.
“Myectomy 3.0 adds mitral valve repair to myectomy at the time of index operation, and online imaging to ensure a tailored myectomy,” Sherrid and colleagues wrote. “Because ... alcohol ablation yields suboptimal relief of gradient and symptoms, and ... is associated with higher mortality, it should not be considered a routine therapeutic choice for patients with medication-resistant obstructive HCM. We believe it should be reserved for those patients who have severe chronic obstructive pulmonary disease, frailty, other causes of increased surgical risk or limited life expectancy.
“How will myectomy 3.0 fit into our armamentarium when new selective potent negative inotropes are added to our therapeutic tool chest,” the authors wrote. “Yogi Berra famously said ‘that it is difficult to make predictions, especially about the future.’”
As Healio previously reported, in the VALOR-HCM trial, mavacamten (Bristol Myers Squibb) reduced the need for septal reduction therapy in patients with obstructive HCM. Mavacamten has not yet been approved by the FDA, but a decision is expected shortly.
Reference:
Perspective
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Milind Y. Desai, MD, MBA
This observational study on 3,859 patients with obstructive HCM from three experienced centers suggests, similar to previous meta-analyses, that septal myectomy is associated with better 10-year survival vs. alcohol septal ablation. As this was not a randomized controlled trial, is it possible to achieve equipoise between alcohol septal ablation and septal myectomy? This lack of equipoise is confirmed as the two groups were unmatched in numbers and important covariates, including age, renal dysfunction, diabetes, coronary disease and hypertension, all known powerful mortality predictors. Given the endpoint was 10-year all-cause mortality, what about comorbidities like cancer?
However, there are other bigger questions to address. There is marked heterogeneity in septal myectomy-related in-hospital mortality, which reaches 16% in low-volume centers. Hence, access to such excellent centers, as in the current study, is logistically not feasible for many patients.
Data from prospective randomized controlled trials (EXPLORER-HCM, MAVA-LTE) involving the cardiac myosin inhibitor mavacamten, suggest an improvement in functional capacity, quality of life, symptoms and relevant biomarkers, in short-term with sustained longer-term improvement. In a recent study (VALOR-HCM), mavacamten also enabled patients to avoid invasive therapies at 16 weeks. Hence, in the future, without a trial of cardiac myosin inhibitors: a) would it be appropriate to get septal myectomy at a low-volume center or alcohol septal ablation in a low surgical risk patient, especially with unfavorable coronary anatomy? b) rather than reliance on observational data, should the dogma that it is “difficult” to do a RCT between myectomy and alcohol ablation be challenged? c) will cardiac myosin inhibitors stand the test of long-term efficacy and safety?
Ultimately, the future is bright for patients with obstructive HCM with an expanded array of available therapies.
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