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.
Comments
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.
Conclusion:
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.
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