In order to assess the long term exercise capacity after percutaneous tranluminal septal myocardial ablation (PTSMA) 23 out of 27 ablated patients with symptomatic HOCM underwent a symptom limited cardiopulmonary exercise treadmill test before the procedure, then after 3 months (early follow-up) and after a mean 7.2 ± 1.0 years (long-term follow-up). The other 4 patients survived, but were excluded from exercise test due to extracardial limitations.
Before PTSMA, mean maximal pressure gradient in the left outflow tract (LVOTGmax) was 82 ± 29 mmHg, 17 patients had NYHA functional class ≥ III and peak oxygen uptake (pVO2) was 18 ± 4 ml/kg/min. PTSMA led to a reduction in mean LVOTGmax (to 29 ± 19 mmHg, p < .0001), improvement of heart failure symptoms (NYHA ≥ III in 1 patient, p < .0001) and an increase of pVO2 (to 22 ± 6 ml/kg/min, p = .0002) at short-term. LVOTGmax, functional class and pVO2 did not change significantly during long-term follow-up compared to early follow-up. However, there was a continuous improvement in percentage predicted pVO2 over time. In summary, PTSMA leads to stable long-term improvement of objectively measured exercise capacity in patients with HOCM and symptoms of heart failure.
PTSMA was introduced for treatment of symptomatic patients with HOCM. Functional capacity in the short-term improves whereas symptomatic and functional long-term follow-up has been discussed in the last decade. Malek et al. report on continous long-term impovement after septal ablation with respect to clinical symptoms and, more important, objectively measured exercise capacity. A potential drawback of the study is the small number of patients who represent the learning curve of group. But, the results support previous reported findings of other groups who reported on continous improvement of clinical symptoms as well as diastolic function, myocardial blood flow, LA dimensions, septal and posterior wall thickness as result of remodelling after successful PTSMA without significant deterioration of systolic function. In these reports reduction of ischaemia and syncope recurrence, as well as the absence of increase in the incidence of malignant ventricular arrhythmias during long-term follow-up, implies a more encouraging profile of reduced sudden death risk.
At this stage it is important to mention that the authors did not observe adverse clinical side effects, especially sudden death, which had been expected in the beginning of interventional induced myocardial infarction. In contrast to these negative expectations further long-term reports had been published, which show that this treatment is both safe and effective. Our group reported on overall survival rate after alcohol septal ablation in a cohort of the first 100 patients treated was 96% at 8 years, while survival without severe symptoms, atrial fibrillation, stroke or ICD implantation was 74%. Taking account of the steep learning curve of alcohol septal ablation, this outcome can be at least paralleled with earlier follow-up studies after surgical myectomy. In addition, reported experience of alcohol septal ablation from a highly esteemed myectomy centre has shown 88% overall survival at 4 years. In a retrospective comparison, this outcome was similar to that of an age and gender matched, but probably less sick, group of patients who underwent surgical myectomy.Overall, a decade of PTSMA has shown that this is a promising therapy for patients with HOCM and symptoms refractory to medical treatment. The need for careful selection of patients has stimulated a debate about the existence and impact of obstruction in the last years. It is therefore pertinent to look for obstruction, identify the patients that could benefit from intraventricular gradient reduction and avoid overuse of interventional treatment.
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