eComment. Septal reduction therapy for hypertrophic cardiomyopathy: the need of experienced centres

I read with great interest the article by Knyshov et al [1]. In fact, the article nicely demonstates the relationship between the electrical conduction disturbances of left ventricular apex-septum and the malfunction of the papillary muscles of the mitral valve, resulting in a critical area of systolic anterior motion (SAM)-septal contact in hypertrophic cardiomyopathy (HCM). Although this article provides acceptable results with dual-chamber pacing in 49 patients with obstructive HCM with evident drug-refractory symptoms, there is no a reliable predictor of success for dual-chamber pacing in HCM with left ventricular outflow tract obstruction (LVOTO) [2].

Based on the 2011 ACC/AHA guidelines for the diagnosis and treatment of HCM3], recommendations for septal reduction therapy can be summarized as follows.

• i) Septal myectomy is indicated in elegible patients with HCM with severe drug-refractory symptoms and LVOTO >50 mmHg associated with septal hypertrophy and SAM of the MV;

• ii) Alcohol septal ablation is recommended when surgery is contraindicated because of serious comorbidities or older age, and due to patient preference;

• iii) DDD pacing is indicated in patients with previously implanted dual-chamber devices for non-HCM reasons, and in suboptimal candidates for septal reduction therapy.

Implantation of dual-chamber pacemaker was proposed as an alternative treatment for patients with severe symptomatic obstructive HCM, but in terms of gradient reduction the results have not been strongly conclusive [4]. Quantitatively, our tools of analysis [3] have led us to establish "how much" septal myectomy can help to treat obstructive HCM, especially in younger, healthy adults. If we were to make a list of recommended treatments for HCM and LVOTO, we could opt to begin with surgical therapy and we would end up with DDD pacing. However, it is difficult enough to work within a guidelines system, which repetitively mentions that septal reduction therapy must be performed in experienced centres. Indeed, the guideline committee [3] recommends an operator threshold volume of 20 procedures or that the operator work within the context of an HCM program with a cumulative procedural volume of at least 50 procedures, with mortality rates <1% and major complication rates <3%, with documented success in both haemodynamic and symptoms benefit for their patients. No objective can be viewed in a vacuum. The question is, with the array of alternatives available, what is the most appropriate choice that can best achieve success according to the level of the development for each given centre. No one mode represents a solution to all of the needs. The choice of the appropriate mode is or should be highly sensitive to inherent characteristics of the medical team. This point has to be recognized above all. We need to address the issue from the daily reality of developing countries, in which experienced centres are often lacking. Perhaps DDD dual-chamber pacing for non-severe obstructive forms of HCM, and the mitral valve replacement for HCM with LVOTO and SAM could be a good solution for these pathologies under the circumstances described above.

Conflict of interest: none declared