Basic Alcohol Septal Ablation Procedure For Hypertrophic Cardiomyopathies

Hypertrophic cardiomyopathy (HCM) is a common genetic heart disease inherited in an autosomal dominant pattern. The prevalence of HCM in young adults has been reported to range from 1:200 to 1:500. Among patients diagnosed with HCM, 30% to 40% will experience adverse events including sudden cardiac death (SCD), progressive limiting symptoms because of left ventricular outflow tract obstruction (LVOTO) or diastolic dysfunction, heart failure symptoms associated with systolic dysfunction, and atrial fibrillation (AF) with the risk of thromboembolic stroke.  A clinical diagnosis of HCM in adult patients can be established by imaging with two-dimensional (2D) echocardiography (TTE) or cardiovascular magnetic resonance (CMR) showing a maximal end-diastolic wall thickness of  ≥ 15 mm anywhere in the left ventricle in the absence of other another cause of hypertrophy in adults.

(LVOTO)  either at rest or with provocation is present in nearly %75 of patients with HCM. The presence of a peak LVOT gradient of ≥ 30 mm Hg is considered to be indicative of obstruction, with resting or provoked gradients ≥ 50 mm Hg generally considered to be the threshold for septal reduction therapy (SRT) in those patients with drug-refractory symptoms. In patients with HCM in whom SRT is indicated, the procedure should be performed at experienced centers (comprehensive or primary HCM centers) with demonstrated excellence in clinical outcomes for these procedures. In adult patients with symptomatic obstructive HCM in whom surgery is contraindicated or the risk is considered unacceptably high because of serious comorbidities or advanced age, alcohol septal ablation when feasible and performed in experienced centers becomes the preferred invasive strategy for relief of LVOTO. Septal reduction by alcohol septal ablation (ASA) avoids sternotomy and, generally, patients experience less pain. Septal reduction by ASA is also advantageous in patients whose frailty or comorbid conditions increase the risk of surgical myomectomy. In centers with experienced interventional teams, procedural mortality of ASA  is low (<1%).

Alcohol septal ablation is a catheter-based intervention that relies on the injection of absolute alcohol into the septal perforator to induce a controlled infarction of the hypertrophied septum and consequently abolish the dynamic outflow obstruction. This gradient reduction has been correlated with a significant clinical improvement in the patient’s symptomatology and with left ventricular remodeling.