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Percutaneous radiofrequency septal reduction for hypertrophic obstructive cardiomyopathy in children

Hypertrophic cardiomyopathy (HCM) accounts for 42% of childhood cardiomyopathy, with a prevalence of 0.47/100,000 and mortality rates in the region of 1- 2%.1-3 A small minority of children with HCM complain of symptoms attributable to left ventricular outflow obstruction (LVOTO). Medical management of LVOTO involves the use of beta blockers, calcium channel antagonists and disopyramide. In those with refractory symptoms, surgical myomectomy remains the gold standard4,5 but this can be technically challenging in children and few centres have the necessary experience. In adults, alcohol septal ablation can be an alternative to surgery, but there is a general consensus that it should not be used in children due to concerns relating pro-arrhythmia and technical limitations.4,5 Isolated case reports and a case series published earlier this year have suggested that an alternative technique, endocardial radiofrequency septal ablation (RFSA) may be useful in the paediatric setting.6,7
Myocardial Disease

In this month’s paper, Sreeram et al report the outcomes of 32 children undergoing percutaneous RFSA for the management of LVOTO. The median age was 11.1 (range 2.9 to 17.5). The his bundle was mapped using LocaLisa and CARTO mapping systems and then a median of 27 lesions (range 10 to 63) were created using a cool tip ablation catheter with transoesophageal echocardiographic guidance. The mean reduction in catheter and Doppler gradients were (78.5 +/- 26.2mmHg to 36.1 +/- 16.5mmHg <0.01) and (96.9 +/- 27mmHg to 32.7 +/- 27.1mmHg, p=<0.01), respectively.
Immediate complications included complete atrioventricular block in 2 patients requiring the implantation of a dual chamber pacemaker, ventricular fibrillation in 2 patients requiring immediate cardioversion and one death due to “a paradoxical increase in LVOTO”. During long term follow up 5 patients required further intervention for LVOTO, one patient required ICD implantation for sustained ventricular arrhythmias and another patient experienced presumed arrhythmic sudden death.
Symptoms of tiredness, exertional dyspnoea, angina and non-arrhythmic syncope were improved in all but one patient. Kaplan-Meier showed freedom from re-intervention at 10 years was 87.5%. The authors conclude that the results are promising and merit further evaluation.


Invasive management of left ventricular outflow obstruction in children is challenging but in large, experienced centres, is associated with a low procedural mortality and good long-term outcomes .8,9 The improvement in LVOTG and symptomatic status produced by RFSA superficially resemble those demonstrated in a small adult series with a lower frequency of conduction disease post procedure.10 However, the lowest measured residual gradient in 12 of the 32 patients was 30mmHg or greater following the initial procedure. The authors also present a Kaplan-Meier to demonstrate that freedom from intervention at 10 years was 87.5%, despite 5 of the 32 patients requiring further intervention for LVOTO. Even more concerning is the high complication rate including one periprocedural death and a second death during follow-up.

There are a number of important principles that should be followed when considering patients for invasive treatment of LVOTO in HCM. In particular, invasive treatment should be considered only when the mechanism of symptoms is clearly understood and patients have received aggressive medical therapy. The type of therapy should primarily be determined by myocardial and valvular morphology. From the data presented, clinical profiling and selection criteria were not available. Symptomatic status at the time of intervention was not defined and only symptoms at the time of presentation were provided. Data relating to cardiac morphology was not provided. Without the afore mentioned it is difficult to comment whether patient selection contributed to the rate of re-intervention seen in this study.
During long term follow up 2 patients developed ventricular arrhythmias. A fundamental concern regarding the use of alcohol septal ablation in this age group relates to the production of pro-arrhythmic scar and increased risk of sudden cardiac death. Evaluation of the scar generated by RFSA and its impact on risk is required.


The data presented suggests that while RFSA can reduce the degree of obstruction, the considerable periprocedural risk and the high frequency of residual obstruction mean that it is not yet ready for routine use in clinical practice. It is important at this early stage to only consider use of the technique in the context of randomised studies with rigid and transparent selection criteria.


  1. Lipshultz S, Sleeper L, Towbin J, et al. The incidence of pediatric cardiomyopathy in two regions of the United States. N Engl J Med 2003;348:1647.
  2. Colan SD, Lipshultz SE, Lowe AM, et al. Epidemiology and cause-specific outcome of hypertrophic cardiomyopathy in children: findings from the Pediatric Cardiomyopathy Registry. Circulation 2007;115:773-81.
  3. Nugent AW, Daubeney PE, Chondros P, et al. Clinical features and outcomes of childhood hypertrophic cardiomyopathy: results from a national population-based study. Circulation 2005;112:1332-8.
  4. Gersh B, Maron B, Bonow R, et al. 2011 ACCF/AHA Guideline 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.
  5. Maron BJ, McKenna WJ, Danielson GK, et al. American College of Cardiology/European Society of Cardiology clinical expert consensus document on hypertrophic cardiomyopathy. A report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents and the European Society of Cardiology Committee for Practice Guidelines. JAmCollCardiol 2003;42:1687-713.
  6. Emmel M, Sreeram N, deGiovanni JV, Brockmeier K. Radiofrequency catheter septal ablation for hypertrophic obstructive cardiomyopathy in childhood. ZKardiol 2005;94:699-703.
  7. Lawrenz T, Kuhn H. Endocardial radiofrequency ablation of septal hypertrophy. A new catheter-based modality of gradient reduction in hypertrophic obstructive cardiomyopathy. ZKardiol 2004;93:493-9.
  8. Theodoro DA, Danielson GK, Feldt RH, Anderson BJ. Hypertrophic obstructive cardiomyopathy in pediatric patients: results of surgical treatment. JThoracCardiovascSurg 1996;112:1589-97.
  9. Minakata K, Dearani JA, O'Leary PW, Danielson GK. Septal myectomy for obstructive hypertrophic cardiomyopathy in pediatric patients: early and late results. AnnThoracSurg 2005;80:1424-9.
  10. Lawrenz T, Borchert B, Leuner C, et al. Endocardial radiofrequency ablation for hypertrophic obstructive cardiomyopathy: acute results and 6 months' follow-up in 19 patients. JACC 2011;57:5.

Notes to editor

Presented by: Dr Vimal Patel and Dr Perry Elliott
The Heart Hospital, UCLH Foundation Trust, UK
The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.

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