Is unsatisfactory outcome of alcohol septal ablation in patients with hypertrophic obstructive cardiomyopathy predictable?

Abstract Background Alcohol septal ablation (ASA) has been introduced for left ventricular outflow tract gradient (LVOTG) reduction in patients with hypertrophic obstructive cardiomyopathy (HOCM). However, some patients may not profit from ASA. Thus, we identified characteristics of patients with unsatisfactory outcome of ASA in a large single-center cohort. Methods Consecutive ASAs between 1997 and 2023, performed at our institution, were retrospectively enrolled. Those ASAs performed in patients with missing follow-up (FU), previous septal reduction therapy (SRT), and atypical HOCM were excluded. Patients with unsatisfactory outcome (PUO) were defined as continuing to meet the guideline criteria for SRT (NYHA ≥III or NYHA ≥II with exertional syncope and resting/exercise-induced LVOTG ≥50mmHg). PUO were compared to patients with good outcome (PGO). Results are expressed in % or median and interquartile range (IQR). Pre-procedural predictors of poor hemodynamic outcome were identified using logistic regression analysis. Results 65 of 1003 patients were PUO (6.5%). Those were younger (48.0 years [40.5-61.8] vs. 57.0 years [IQR 47.0-67.0] in PGO; p=0.0030), more often reported syncope at baseline (35.4% vs. 22.2% in PGO; p=0.0214), and had lower body-mass-index (26.4kg/m2 [23.8-29.2] vs. 27.7kg/m2 [25.2-23.1] in PGO; p=0.0160). In PUO, resting LVOTG was higher at baseline (53.0mmHg [24.5-82.0]) than in PGO (40.0mmHg [22.0-75.0]; p=0.0292; Table 1). Differences in sex, family history of sudden cardiac death, dyspnoea, medication, and interventricular septum diameter (IVSD) were not observed at baseline (all p>0.05; Table 1). Age (OR 1.023; CI: 1.005-1.042; p=0.0129), syncope at baseline (OR 1.890; CI: 1.049-3.324; p=0.0296), and BMI (OR 1.072; CI: 1.007-1.145; p=0.0355) were found to independently influence poor hemodynamic response to ASA using multiple logistic regression controlling for confounders. However, sex, baseline IVSD, and LVOTG were not found to influence poor hemodynamic outcome (p>0.05). There were no differences with regard to the number of embolized branches (1 in both groups), the size of the balloon used to cover the septal branch (1.5mm in both groups), the volume of ethanol (PUO: 1.4ml [1.0-2.0]; PGO: 1.5ml [1.2-2.0]), or creatine kinase release (PUO: 879.0U/l [375.0-1187.0]; PGO: 842.0U/l [501.5 - 1234]) (all p>0.05). At 6-months-FU, PUO had significantly higher IVSD (18.0mm [13.5-22.0] vs. 16.0mm [12.0-19.0] in PGO; p=0.008), higher resting LVOTG (31.0mmHg [20.0-55.5] vs. 14.0mmHg [10.0-22.0] in PGO; p<0.0001) and higher exercise-induced LVOTG (105.0mmHg [84.5-143.0] vs. 35.0mmHg [22.0-64.0] in PGO; p<0.0001). Conclusion ASA was overall effective with only few patients experiencing unsatisfactory outcome. Syncope, age, and BMI were found predicting poor hemodynamic outcome.Baseline characteristics