Through Thick and Thin

Patients with symptoms caused by hypertrophic obstructive cardiomyopathy are treated with β-blockers, verapamil, and disopyramide.1,2 Novel drugs are under development. The minority of patients whose symptoms interfere substantially with lifestyle despite optimal pharmacological management may be offered septal reduction therapy with ablation or myectomy. Other mechanical therapies, including short AV delay pacing, mitral valve replacement, and percutaneous mitral valve repair, are used in some cases. Although opinions on the relative merits of septal ablation and myectomy differ, optimal recommendations can be made for individual patients based on patient characteristics and patient preference.3 Based on anecdotal experience, marked septal hypertrophy (≈30 mm or more) has been considered a factor that favors myectomy over ablation. Data supporting this impression have until now been lacking. At the other end of the septal thickness spectrum, the presence of only mild hypertrophy (≈15 mm or less) is considered to be a relative contraindication to both septal ablation and septal myectomy because of what is judged to be an enhanced risk of creating a ventricular septal defect.See Article by Lu et al The American College of Cardiology Foundation/American Heart Association guidelines, published in 2011, state that “the effectiveness of alcohol septal ablation is uncertain in patients with HCM with marked (ie, >30 mm) septal hypertrophy, and therefore the procedure is generally discouraged in such patients.”4 The 2014 European Society of Cardiology guidelines state that “septal ablation may be less effective in...patients with very severe hypertrophy (≥30 mm), but systematic data are lacking.”5 Indeed, previous studies designed to assess predictors of success of septal ablation failed to demonstrate definitively that septal thickness is a determinant of success.Chang et al6 reported their outcomes in the …