Alcohol Septal Ablation Rivals Myectomy for Obstructive Hypertrophic Cardiomyopathy

Patients with obstructive hypertrophic cardiomyopathy can achieve good long-term outcomes with alcohol septal ablation that rival those of surgical treatment in terms of symptom relief and survival, according to a study published online October 17, 2012, ahead of print in Circulation. However, in both the study and an accompanying editorial, researchers stress that experience is crucial to the success of the percutaneous technique.

Investigators led by Paul Sorajja, MD, of the Mayo Clinic (Rochester, MD), evaluated outcomes for 177 patients who underwent septal ablation for obstructive hypertrophic cardiomyopathy at their institution between December 1998 and August 2010. Approximately 80% had left ventricular outflow tract obstruction at rest on echocardiography (gradient ≥ 30 mm Hg), with latent obstruction present in the remaining 20% of patients.

Septal ablation outcomes were compared with those of age- and gender-matched patients who underwent surgical myectomy at the same institution between 1983 and 2001 as well as against expected survival in the general population.

Similar Survival Rates

Procedural success for septal ablation was 74.6%, with a median residual left ventricular outflow tract gradient of 5 mm Hg at rest. There were 2 in-hospital deaths in the septal ablation group, both were in patients who had presented with cardiogenic shock. Procedural and in-hospital complications were higher with septal ablation than with myectomy (28.8% vs. 5.6%; P < 0.0001).

At 5.7-year follow- up, survival free of all mortality was 79% with the percutaneous treatment. This figure was similar to the expected survival for a comparable general US population (79%), and similar to the age and gender-matched cohort of surgical myectomy patients (79%; P = 0.64 vs. ablation). Documented sudden cardiac death or death from unknown cause in patients receiving septal ablation occurred at an incidence of 1.31 (95% CI 0.60-2.38) per 100 person-years of follow-up. For all-cause death, the incidence per 100 person-years of follow-up was 2.51 (95% CI 1.53-4.00).

In the ablation group, 8-year survival free of the combined endpoint of death and need for repeat septal ablation or myectomy was 69.8% (95% CI 60.9-78.8%). Post-ablation left ventricular outflow tract gradient was an independent predictor of all-cause mortality (RR 1.04; 95% CI 1.01-1.07; P = 0.004).

Experienced Operators Key to Success

According to the study authors, the data should be interpreted with caution since septal ablation at their institution is performed by only select, dedicated invasive operators and cannot be easily extrapolated to less experienced centers. Another limitation of the analysis is that it did not examine the potential impact of subacute remodeling and changes in left ventricular outflow tract gradient in follow-up on long-term outcome.

“Our findings support the need for a greater understanding of patient selection for septal ablation and further technical advances to improve procedural success,” Dr. Sorajja and colleagues write. Since complications were more frequent with septal ablation than with surgery, they say, informed consent “with shared decision-making using an integrated team approach is an elemental component of the management of these complex patients.”

Overall, the study authors suggest the data “support the role of septal ablation in the management of patients with drug-refractory symptoms due to obstructive [hypertrophic cardiomyopathy] when performed by experienced operators.”

In Agreement with Current Guidelines

In an editorial accompanying the study, Eugene Braunwald, MD, of Brigham and Women’s Hospital (Boston, MA), concludes that the study provides further support for American College of Cardiology/American Heart Association guidelines for the treatment of hypertrophic cardiomyopathy published in 2011. The guidelines list septal ablation as a Class I indication and echo the concerns of Dr. Sorajja and colleagues by stating that “septal reduction therapy should be performed only by experienced operators . . . and only for the treatment of patients with severe drug-refractory symptoms and [left ventricular outflow tract].”

The guidelines provide a Class IIa recommendation for surgical myectomy, calling it “the first consideration for the majority of eligible patients with [hypertrophic cardiomyopathy].” They further state that alcohol septal ablation can be beneficial in select patients “when surgery is contraindicated, or the risk is considered unacceptable because of serious co-morbidity or advanced age.”

According to Dr. Braunwald, much of the early work on hypertrophic cardiomyopathy was conducted by the National Heart, Lung, and Blood Institute, which has extensive favorable experience with prospective registries.

“It would now be quite appropriate for the institute to organize a comparison of these 2 techniques of septal reduction which would be relatively inexpensive and cost-effective at a time of fiscal stringency,” he observes.

 

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Sources:
1. Sorajja P, Ommen SR, Holmes Jr DR, et al. Survival after alcohol septal ablation for obstructive hypertrophic cardiomyopathy. Circulation. 2012;Epub ahead of print.

2. Braunwald E. Obstruction in hypertrophic cardiomyopathy: How often does it occur? Should it be treated? If so, how? Circulation. 2012;Epub ahead of print.

3. Gersh BJ, Maron BJ, Bonow RO, et al. 2011 ACC/AHA guidelines for the diagnosis and treatment of hypertrophic cardiomyopathy: A report of the American College of Cardiology Foundation; American Heart Association Task Force on Practice Guidelines. Circulation. 2011;Epub ahead of print.

 

 

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