Indication for alcohol septal ablation
Criteria for patients who are deemed suitable for ASA include; New York
Heart Association (NYHA) class III-IV, LVOT resting gradient
>30mmHG or >50mmHG on provocation, evidence of
systolic anterior motion (SAM) of the mitral valve leaflet, septal wall
thickness >16mm. [6] Various centres will have their
own criteria for patient selection for ASA, on the whole these tend to
be based on symptomology, LVOT gradients and existing o-morbidities.
Concomitant significant coronary artery disease or valvular pathologies
need to be ruled out as these patients will benefit from cardiac surgery
rather than ASA. Favourable coronary anatomy is also crucial to outcomes
as easily accessible septal branches allow for uncomplicated procedures.
[7] The 2011 ACCF/AHA guidelines state that surgical myectomy should
be gold standard for drug refractory HOCM and advise against the use of
ASA in those with marked septal hypertrophy (>30 mm), in
younger patients, in mid ventricular obstruction, and in those with
concomitant disease that requires surgical intervention. They
particularly advised against both surgical and percutaneous intervention
in those who are asymptomatic or have normal exercise tolerance.
[2,8]. Indications have been summarised in Table 1
NYHA and CCS are useful indicators of symptoms, however they remain
highly subjective. Jones et al. suggest the use of other tests in order
to identify patients suitable for ASA. One such test is cardiopulmonary
exercise testing which can be used in HOCM patients with mild symptoms,
where peak VO2 is associated with NYHA class. 6-minute walk test can
also provide an objective measure of exercise tolerance. Kansas City
cardiomyopathy questionnaire involves clinical and non-clinical aspects
as part of its scoring system and emphasises the importance of quality
of life in choosing candidates for ASA. [9] Table 2 shows the
calculation of the risk of sudden cardiac death in HOCM and how it can
be used to predict mortality in those with severe HOCM who remain
untreated.