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]