Background Prior national data showed a substantial in‐hospital mortality in septal myectomy (SM) with an inverse volume–outcomes relationship. This study sought to assess the contemporary outcomes of septal reduction therapy and volume–outcome relationship in obstructive hypertrophic cardiomyopathy. Methods and Results All septal reduction therapy admissions between 2010 to 2019 in the United States were analyzed using the National Readmission Databases. Hospitals were stratified into tertiles of low‐, medium‐, and high‐volume based on annualized procedural volume of alcohol septal ablation and SM. Of 19 007 patients with obstructive hypertrophic cardiomyopathy who underwent septal reduction therapy, 12 065 (63%) had SM. Two‐thirds of hospitals performed ≤5 SM or alcohol septal ablation annually. In all SM encounters, 482 patients (4.0%) died in‐hospital post‐SM. In‐hospital mortality was <1% in 1505 (88.4%) hospitals, 1% to 10% in 30 (1.8%) hospitals, and ≥10% in 167 (9.8%) hospitals. There were 63 (3.7%) hospitals (averaging 2.2 SM cases/year) with 100% in‐hospital mortality. Post‐SM (in low‐, medium‐, and high‐volume centers, respectively), in‐hospital mortality (5.7% versus 3.9% versus 2.4%, P =0.003; adjusted odds ratio [aOR], 2.86 [95% CI, 1.70–4.80], P =0.001), adverse in‐hospital events (21.30% versus 18.0% versus 12.6%, P =0.001; aOR, 1.88 [95% CI, 1.45–2.43], P =0.001), and 30‐day readmission (17.1% versus 12.9% versus 9.7%, P =0.001; adjusted hazard ratio, 1.53 [95% CI, 1.27–1.96], P =0.001) were significantly higher in low‐ versus high‐volume hospitals. For alcohol septal ablation, the incidence of in‐hospital death and all other outcomes did not differ by hospital volume. Conclusions In‐hospital SM mortality was 4% with an inverse volume‐mortality relationship. Mortality post‐alcohol septal ablation was similar across all volume tertiles. Morbidity associated with SM was substantial across all volume tertiles.

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Introduction: Recognition of transthyretin amyloid cardiomyopathy (ATTR-CM) as a cause of heart failure has increased over the past decade. ATTR-CM, particularly wild type (wtATTR-CM), is considered to mainly affect men. Tafamidis was approved by the FDA for the treatment of ATTR-CM based on the results of the ATTR-ACT trial, which only included 13 women with wtATTR-CM (out of 335). We investigated the proportion of women diagnosed with ATTR-CM over time and compared their presenting characteristics to men. Hypothesis: Improved recognition of ATTR-CM has uncovered a higher prevalence of ATTR-CM in women compared to historical estimates. Methods: We compared the presenting characteristics of women to men diagnosed with ATTR-CM. We also compared the proportions of women with ATTR-CM diagnosed before 2019 with those diagnosed 2019-2022. Subgroup analysis of wtATTR-CM patients was performed as well. Results: Over the study period, 140 consecutive patients (81% wild type, 11.4% women) with ATTR-CM were included. The rate of diagnosis of hereditary ATTR-CM in women did not change from pre 2019 (4/69 or 6%) to 2019-2022 (5/71 or 7%). However, for wtATTR-CM, there were 0 women and 51 men diagnosed prior to 2019 as compared to 7 women (11%) and 62 men from 2019-2022. There were several differences in the presenting characteristics between men and women in the combined ATTR-CM group (Table). However, in the wtATTR-CM group, the only significant differences were higher left ventricular ejection fraction and smaller systolic and diastolic diameters in women (Table). Conclusions: There has been a rapid increase in the rate of diagnosis of wtATTR-CM in women. Ongoing education and a changing diagnostic landscape will redefine wtATTR-CM epidemiology.

Introduction: Patients with obstructive hypertrophic cardiomyopathy (oHCM) frequently present with heart failure symptoms refractory to medical therapy and require septal myectomy (SM). The magnitude of benefit from SM is thought to be better than the recently reported data from EXPLORER-HCM and REDWOOD-HCM trials. We prospectively investigated the association between SM, patient-reported 12-item Kansas City Cardiomyopathy Questionnaire (KCCQ-12) and physician-reported NYHA class in a community-based cohort of oHCM. Hypothesis: SM ± submitral valve repair is associated with improvement in NYHA class and KCCQ-12 but with a varying magnitude of benefit. Methods: We conducted a prospective cohort study of 108 patients with oHCM who underwent SM (48% women, age 59 (45, 67) years). KCCQ-12 and NYHA class were assessed prospectively prior to SM, at 1-3 months post-SM and at 4-12 months post-SM. KCCQ-12 is reported as an additive score. Data are reported as median values (IQR). Results: Pre-SM, LVEF was 70% (65, 75) while resting and Valsalva LVOT gradients were 42 (22, 90) and 87 (53, 119) mm Hg, respectively. Post-SM, median LVEF was 65% (60, 69) with respective resting and Valsalva LVOT gradients of 11 (8, 16) and 16 (11, 28) mm Hg (all p<0.001). NYHA Classes ≥III decreased in prevalence from 71% to 13% to 3% after SM (p<0.001). Pre-SM, KCCQ-12 was 39 (31, 48), which improved to 51 (41, 57) at 1-3 months post-SM and 58 (52, 63) at 4-12 months post-SM (p<0.001). Changes in NYHA Class distribution and KCCQ-12 scoring after SM are shown in Figure 1. Conclusion: SM was associated with significant improvement in KCCQ-12 and NYHA class in a community-based cohort of oHCM. The inability to conduct blinded NYHA class and KCCQ-12 assessment post-SM is a major limitation given EXPLORER-HCM showed 31% placebo effect on NYHA class. Further contemporary comparative studies of SM and cardiac myosin inhibitors are needed.

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