Outcomes of alcohol septal ablation
Several centres have reported promising results in both short- and
long-term outcomes of patients who undergo ASA. Rosa et al. chose to use
a LVOT gradient >50mmHg at rest and >70 mmHg
on provocation as part of their selection criteria. 92.5% of their
patients had NYHA class III or IV prior to ASA, they observed
>50% reduction of LVOT gradient in 85.7% of their patient
group within a year of the procedure. The most common procedural
complication was atrioventricular (AV) block which was 45% however this
was either transient or permanent, as only 8.8% required permanent
pacemaker (PPM) implantation. In hospital mortality was low at 3.8% and
12.5% required redo ASA or myectomy. The majority of their patients
(77%) showed improved symptoms and were found to have NYHA class I or
II in follow up. [10] An et al. compared the long-term survival of
233 patients with HOCM who underwent ASA and 297 patients with
non-obstructive hypertrophic cardiomyopathy (NOHCM), they included
patients with LVOT gradients >50 mmHg at rest and on
provocation as part of their selection criteria for ASA. This study was
targeted at a younger patient group; the HOCM and NOHOCM had an average
age of 48.7 and 46.2 respectively. They found low peri-procedural
mortality (0.89%), 4% developed ventricular arrhythmias and only
0.44% required PPM implantation. They found a significant reduction in
LVOT pressure gradient immediately post ASA and at the 3 month follow
up. 10-year survival from all-cause mortality was 94.7% for the ASA
group and 92.9% in the NOHCM group. 6 out of the 9 patients who
suffered from ventricular arrhythmias were <40 years of age
which may suggest that lower age may have a higher incidence of
ventricular arrhythmias in the periprocedural period. ASA is typically
targeted at patients with advanced age and more studies need to be
conducted in younger patient age groups to understand the safety of the
procedure. [11]
The ESC guidelines suggest invasive treatment to those individuals with
LVOTO >50 mmHg, and NYHA class III-IV despite maximal drug
therapy. Centres may alter their selection criteria to include those
with NYHA class II in the context of severe SAM related mitral
regurgitation (MR) or AF. [12] Veselka et al. observed the effect of
ASA on mild symptomatic patients, those with NYHA class II symptoms were
selected for the study. These patients did however have a LVOTO
>50 mmHg at rest or provocation. They found a 77%
reduction in LVOTO gradient during clinic follow up with 69% patients
with NYHA class I symptoms. Only 9.3% required repeat septal reduction
therapy due to inadequate symptomatic relief. [13]
Kashtanov et al. performed a 10 year follow up of patients who underwent
ASA. They found hospital mortality to be at 0%, and PPM implantation at
7.5%. Pressure gradients at rest and provocation significantly
decreased when compared to baseline and 10-year values. Though there
were no statistical differences between the 1 year and 10-year
gradients. The same pattern can be seen for interventricular septum
(IVS) thickness. Ejection fraction and left atrial diameter values
remained stable, though end diastolic diameter followed a negative trend
at the 1 year and 10 year stages. NYHA class had decreased between pre
procedure and 1 year follow up but has not changed at the 10 year follow
up. Canadian cardiovascular society (CCS) class of angina did not
statistically differ between 1 year and 10-year values. 2 patients
required PPM at 9 and 11 years respectively. [14] Jahnlova et al.
studied the long-term effect of ASA on patients >60 years
of age. 90% of selected patients suffered from NHA class III dyspnoea,
while 75% had both dyspnoea and angina. 2.6% died during the first
month, post procedure transient complete AV block was seen in 24.4%
with 11.5% needed PPM. Sustained ventricular tachycardia or ventricular
fibrillation occurred in 3.2% of patients. In terms of long term follow
up 81% of patient had < NYHA class II dyspnoea and 76% had
maximal LVOT gradient <30 mmHg at rest or provocation. Only
3.9% required repeat ASA and 1.3% needed SM. 51% of all mortality
events were due to cardiovascular causes and compared with the expected
mortality in the sex and age matched general population, patients
>60 years after ASA showed greater mortality. [15]
ASA is more commonly chosen for patients with hypertrophy at the mitral
valve level with SAM, less commonly around 5% of HCM patients can
develop mid ventricular obstruction leading to papillary muscle
hypertrophy and LV apical aneurysm; SAM with mid ventricular and outflow
tract obstruction can also be seen in these patients. Tengiz et al.
report a case where ASA was performed on a symptomatic individual with
mid ventricular HOCM, the first septal branch was used and 3 ml were
injected into the vessel. Post procedure echocardiogram revealed reduced
in IVS, left atrial dimension, and mild MR without SAM, patient was
asymptomatic during follow up. ASA in mid ventricular HOCM still
requires extensive study but may in the future be included as part of
the morphological criteria for ASA. [16] Barwad et al. interestingly
report a case where a patient with known HOCM who developed sepsis due
to cholangitis underwent ASA. Endoscopic retrograde
cholangiopancreatography (ERCP) had failed and systemic hypotension
despite fluid and inotrope support worsened LVOT obstruction with a
resting LVOT gradient of 90mmHg. Haemodynamic instability in the context
of sepsis can result in unfavourable outcomes in those with HOCM, as
volume depletion can worsen LVOT obstruction and inotropes in this
setting can make the obstruction worse. ASA was performed as a form of
rescue therapy and was successful in reducing LVOT gradient and allowed
the patient to overcome the infection. [17] Kulic et al. report a
case of a young individual who had SM and developed symptoms 4 years
after the initial intervention due to progression of disease, underwent
ASA and achieved reduction in LVOT gradient, indicating a role of ASA as
a less invasive method for those who require re-intervention. [18]