Indications for and individualization of septal reduction therapy

Abstract

The importance of left ventricular outflow tract obstruction in a large subset of patients with HCM and drug-refractory symptoms, as well as the value of septal reduction therapy (surgical myectomy or alcohol septal ablation), has been demonstrated. However, determining the precise cause of symptoms in the HCM patient, and specifically implicating outflow tract obstructive physiology, can be quite challenging. Accordingly, a detailed and comprehensive morphologic and physiologic evaluation of the HCM patient is of paramount importance to determine which patients may benefit from septal reduction therapy. Patients should be considered for septal reduction therapy when (a) symptoms are clearly and primarily attributed to obstructive HCM despite optimal medical therapy, (b) symptoms encompass severe heart failure or angina (NYHA or CCS class III/IV), recurrent obstruction-related syncope, or recurrent clinical decompensation due to refractory paroxysmal atrial fibrillation, (c) a gradient ≥50 mmHg can be demonstrated on optimal medical therapy, and (d) obstruction is clearly dynamic and subvalvular, resulting mainly from septum-to-anterior mitral leaflet contact. Surgical myectomy has been the traditional gold-standard invasive therapy. Alcohol septal ablation (ASA) is a minimally invasive catheter-based alternative with less patient discomfort and more rapid recovery; however, only patients with certain anatomic criteria are candidates. Evidence from non-randomized studies suggests that ASA and surgical myectomy result in similar short- and long-term outcomes with respect to hemodynamic and functional improvements, with greater propensity for pacemaker placement with septal ablation. Based on comprehensive assessment of clinical symptoms, associated co-morbidities, echocardiographic, electrocardiographic, and angiographic features, some patients are better suited for myectomy while others are better suited for ASA. This chapter will review indications for septal reduction therapy and how to individualize the selection of the appropriate septal reduction procedure in clinical practice.