Follow up
Long-term follow up is vital in order to ascertain the effects of ASA in
patients with drug refractory HOCM. Usual methods include yearly
echocardiograms looking into LVEF, septal wall thickness, valvular
function, LV systolic and diastolic function. Akita et al. propose the
use of brain natriuretic peptide (BNP) as a prognostic indicator in
patients who have had ASA. BNP is expressed in the ventricular myocytes
during stress and can appear elevated in patients with LVOTO and
diastolic dysfunction. They found reduction in BNP post ASA; with
greater reduction up till the 3-month period and plateaus until the
12th month, greater declines were seen in the good
responder group (Drop in NYHA class >1) [26]
Exercise tolerance along with symptomology is a useful indicator of the
therapeutic effects of ASA. Fernandes et al. used monitored the exercise
tolerance of their ASA during follow up using the treadmill test. The
patients chosen for the study had NYHA class III-IV dyspnoea; they found
significant improvement in NYHA class as well as LVOT gradient at the 3
month and 1 year phase. The treadmill time significantly improved 3
months post ASA and remained elevated though fewer patients were
subjected to the treadmill test in the latter stages of follow up.
[6]
Cardiac MRI was used by Sohns et al. compare the short-term results of
ASA when compared to conventional echocardiography and cardiac
catheterization. CMR was able to assess the scar tissue formed as a
result of ASA; it showed a correlation between scar size and post
extrasystolic gradient reduction, whereas echocardiogram did not record
similar findings. CMR also identified that greater areas of scar tissue
were associated with higher doses of ethanol. CMR may be able to perform
a functional assessment on tissue by measuring flow velocity and flow
volume, it can also assess myocardial viability and be used to follow
ventricular remodelling. CMR may be useful as a non-invasive tool in
conjunction with other imaging techniques to assess the effectiveness of
ASA in the short and long term. [33]