Rowin, Ethan J.

Background: Treatment of progressive heart failure, due to left ventricular (LV) outflow tract obstruction has been a major component of hypertrophic cardiomyopathy (HCM) disease management for 50 years. Septal myectomy has been the primary treatment option to abolish gradients and relieve heart failure symptoms. The role of myectomy in HCM management has depended on effectiveness in relieving heart failure symptoms, but also an acceptable operative risk. Methods: Over the most recent 15-year period, we reviewed 3,700 consecutive isolated myectomy operations performed at major North American HCM institutions. Composite operative mortality (first 30 days) was only 0.4%. Seventeen operative deaths were at ages 24 to 82 (≥70 years), and only 6 occurred after 2010. Notably, 2 of the 4 Mayo Clinic deaths were in patients with prior alcohol septal ablation. Septal myectomy, when performed in experienced HCM centers, was much safer when compared to operative mortality with coronary artery bypass grafting (2.3%); valve replacement (3.5%); mitral valve replacement specifically (5.7%) (STS Database), similar to atrial or ventricular septal defect closure and 15-fold less than myectomy in community hospital or low volume surgical settings. Conclusions: Surgical myectomy performed in dedicated HCM centers with experienced surgeons and staff is one of the safest open-heart procedures currently practiced, with a mortality rate as low as 0.4%. The large mortality discrepancy for myectomy between community hospitals and dedicated HCM centers underscores that this operation should be considered a specialized procedure best performed in high volume HCM institutions.

Background: Sodium-glucose cotransporter-2 inhibitors (SGLT2i) have been demonstrated to improve outcomes in congestive heart failure (HF). However, their effect in hypertrophic cardiomyopathy (HCM) is unknown. Research Question: Can SGLT2i improve clinical outcomes in HCM patients? Methods: Using TriNetX Global Research Network from March 2013 to February 2021, patients diagnosed with HCM (ICD-10 codes I42.1, I42.2) were identified and categorized into 2 groups: those on SGLT2i vs. those who are not. To avoid inclusion of other causes of left ventricular hypertrophy, patients with aortic stenosis or systemic hypertension were excluded. Propensity score matching (PSM) was used to limit confounders. Primary outcome was all-cause mortality and secondary outcomes were HF exacerbation, all-cause hospitalization, and documented cardiovascular symptoms (chest pain, dyspnea, palpitations, or leg edema) over a 2-year follow-up period. Results: A total of 27,561 HCM patients were identified; 408 (1.5%) on SGLT2i and 27,153 (98.5%) were not. Patients on SGLT2i were older (55 ± 15 vs. 48 ± 19, p<0.01) and had more comorbidities, including a nearly 6-fold higher prevalence of diabetes mellitus (44% vs. 7%, p<0.01) and congestive HF (65% vs. 10%, p<0.01). After PSM, each group consisted of 355 patients. HCM patients on SGLT2i had lower rates of all-cause mortality (OR 0.22 [95% CI: 0.12, 0.39]; p<0.01), hospitalizations (OR 0.72 [95% CI: 0.53, 0.98]; p=0.04), and cardiovascular symptoms (OR 0.71 [95% CI: 0.52, 0.97]; p=0.029) when compared to patients not on SGLT2i. There was no statistical difference in the rate of HF exacerbation (OR 0.82 [95% CI: 0.54, 1.24]; p=0.3). Conclusion: In this large dataset, SGLT2i use in a select subset of HCM patients was associated with improved survival, less hospitalizations, and fewer cardiovascular symptoms. These data support future randomized trials to evaluate the efficacy and safety of SGLT2i in more diverse HCM patient populations.

Background: Marked septal hypertrophy is considered a requirement for effective myectomy in obstructive hypertrophic cardiomyopathy (HCM), with mitral valve replacement recommended as the alternative strategy in patients with minimal hypertrophy. However, it remains uncertain whether relief of obstruction can be effectively abolished without mitral valve replacement in patients with minimal septal wall thickening. Methods: Of 500 patients who underwent surgical myectomy from 2004 to January 2014, 21 (4.2%) were identified with a maximum LV wall thickness ≤ 15mm and constitute the study cohort. Results: All 21 patients (56 ± 10 years old; 62% male) were followed for advanced heart failure symptoms refractory to drug therapy with a maximal septal wall thickness of 13.6 ± 1.7 mm (range: 10-15 mm; ≤ 12 mm in 5 patients). Outflow obstruction ≥ 30 mmHg due to mitral valve-septal contact was present after exercise in 17 of 21 patients (range: 50-150 mmHg), and under resting conditions in 4 patients (range: 30-65 mmHg). In all patients, surgical relief of obstruction consisted of muscular resection of the basal septum with revision of abnormal and apically displaced papillary muscles, which were judged intraoperatively to be contributing to obstruction. In addition, in 10 patients (47%) myectomy alone was not sufficient to relieve obstruction due to the limited opportunity for septal reduction and adjunctive mitral valve repair was performed to shorten an elongated anterior leaflet. No patient required mitral valve replacement or incurred a ventricular septal defect. Post-operatively, 4 patients developed complete heart block requiring permanent pacemaker (1 patient with pre-operative right bundle branch block) and 1 had a cerebrovascular event. At most recent follow up 18 ± 19 months post-myectomy, septal thickness was reduced to 10 ± 2 mm, no patient had an outflow gradient at rest or with provocation, and all patients were alive with the majority asymptomatic (class I: n=13; 62% and class II n=8; 38%). Conclusion: In patients with minimal septal hypertrophy, outflow obstruction can be effectively abolished with surgical myectomy and adjunctive mitral valve repair with a small increased risk of heart block, but without the need for mitral valve replacement.