Hospital Procedural Volume and Clinical Outcomes Following Septal Reduction Therapy in Obstructive Hypertrophic Cardiomyopathy

Invasive Management of Hypertrophic Cardiomyopathy With Clinically Important Obstruction: Surgical Myectomy Is Superior, but Only When Accessible

For patients with hypertrophic cardiomyopathy (HCM), a thickened intraventricular septum and systolic anterior motion of the mitral valve (SAM) can contribute to significant left ventricular outflow tract obstruction (LVOTO), mitral regurgitation, and debilitating symptoms. Current guidelines recommend septal reduction therapy through alcohol septal ablation or surgical septal myectomy for patients whose symptoms persist despite medical therapy. Although alcohol septal ablation is a less invasive treatment option, it is not suitable for patients with septal perforator branch anatomy that is not compatible with the procedure, those with midcavitary obstruction, and patients in whom the mechanism of LVOTO is primarily related to SAM. Septal ablation also has a notably higher rate of atrioventricular block requiring permanent pacemaker insertion, and the need for reintervention has been reported to be 15% or more. In contrast, septal myectomy offers direct visualisation and can address thickened septum and mitral valve (MV) anomalies. It can be used to treat a wider variety of anatomies, with lower rates of reoperation. Aside from the more invasive nature of the procedure, a major limitation of septal myectomy, however, is access, because relatively few surgeons specialise in the procedure. This is important because there is a significant correlation between procedural volumes and outcomes. Patients should be evaluated by a multidisciplinary heart team to ensure that they are aware of all treatment options. In this review, we explore the 2 methods of septal reduction therapy and highlight the need for further training of septal myectomy surgeons to ensure access to optimal septal reduction therapies for Canadian patients with HCM.

The Revolution of Cardiac Myosin Inhibitors in Patients With Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy worldwide and causes significant morbidity and mortality. For decades, medical treatment options have been limited and untargeted, with frequent need for invasive interventions not readily accessible to many HCM patients. More recently, our understanding of the genetic basis and pathophysiologic mechanism of HCM has grown significantly, leading to the discovery of a new class of medications, cardiac myosin inhibitors (CMIs), that shift myosin into the super-relaxed state to counteract the hypercontractility in HCM. Subsequent clinical trials have proven the mechanism and efficacy of CMIs in humans with obstructive HCM, and additional trials are under way in patients with nonobstructive HCM. With favourable results in the completed clinical trials and ongoing research on the horizon, CMIs represent a bright new era in the targeted management of HCM. This review is focused on the discovery of CMIs, provides a summary of the results of clinical trials to date, provides clinicians with a roadmap for implementing CMIs into practice, and identifies gaps in our current understanding as well as areas of ongoing investigation.

Impact of concomitant surgical interventions on outcomes of septal myectomy in obstructive hypertrophic cardiomyopathy

BACKGROUND

Septal myectomy (SM) is offered to symptomatic patients with obstructive hypertrophic cardiomyopathy (oHCM) despite medical therapy. Frequently, patients undergo concomitant planned or ad-hoc mitral valve replacement (MVR), aortic valve replacement (SAVR), or coronary artery bypass grafting (CABG).

OBJECTIVES

We sought to assess characteristics and outcomes of patients with oHCM undergoing concomitant surgical interventions at the time of SM.

METHODS

The National Readmission Databases were used to identify all SM admissions in the United States (2010-2019). Patients undergoing SM were stratified into: isolated SM (±MV repair), SM + CABG only, SM + MVR, SM + SAVR, and SM + MVR + SAVR. Primary outcomes were in-hospital mortality, in-hospital adverse events, and 30-day readmission.

RESULTS

12,063 encounters of patients who underwent SM were included (56.1% isolated SM, 9.0% SM + CABG only, 17.5% SM + MVR, 13.1% SM + SAVR, and 4.3% SM + MVR + SAVR). Patients who underwent isolated SM were younger (54.3 vs. 67.1 years-old, p < 0.01) and had lower overall comorbidity burden. In-hospital mortality was lowest in isolated SM, followed by CABG only, SM + SAVR, SM + MVR, and SM + SAVR+MVR groups (2.3% vs. 3.7% vs. 5.3% vs. 6.7% vs. 13.7%, p < 0.01), respectively. SM with combined surgical interventions was associated with higher adverse in-hospital events (24.3% vs. 11.1%, p < 0.01) and 30-day readmissions (16.9% vs. 10.4%, p < 0.01). MV repair performed concomitantly with SM was not associated with increased in-hospital mortality (3.9% vs. 3.4%, p = 0.72; aOR 0.99; 95% CI: 0.54-1.80, p = 0.97]) or adverse clinical events.

CONCLUSIONS

In SM for oHCM, patients undergoing concomitant surgical interventions were characteristically distinct. Aside from MV repair, concomitant interventions were associated with worse in-hospital death, adverse in-hospital events, and 30-day readmission.

Treatment Strategies for Hypertrophic Cardiomyopathy: Alcohol Septal Ablation and Procedural Step-by-Step Technique

Alcohol septal ablation (ASA) is a well-established procedure for septal reduction therapy in patients with obstructive hypertrophic cardiomyopathy, significant at rest or provocable outflow tract gradients, and medically refractory symptoms. This percutaneous approach to relief of obstruction and eventual cardiac remodeling involves the infusion of a small quantity of ethanol into an appropriately targeted septal artery that is feeding the basal septum to create an iatrogenic and controlled focal infarction. Early akinesia is followed by subsequent thinning and remodeling, which widens the outflow tract, reducing or eliminating the obstruction. Historically, the use of ASA was reserved primarily for high-risk surgical candidates; however, more contemporary data suggest similar outcomes in the short-term and long-term safety of the procedure and overall effectiveness in relieving obstructive symptoms when it is performed in broader populations at experienced centers. Therefore, the current guidelines published in 2020 support ASA as a class 1 indication, similar to its open-heart surgical counterpart, surgical myectomy, when no concomitant significant coronary or valve surgical indication exists. This article summarizes contemporary management of patients with hypertrophic cardiomyopathy who were selected for ASA and details procedural methods and outcomes.

Age-Based Outcomes in Patients Who Underwent Septal Reduction Therapy

There are no national data on age-based outcomes of septal reduction therapy. Using the National Inpatient Sample, we included all adult patients who underwent septal myectomy (SM) or alcohol septal ablation (ASA) from 2005 to 2019. The primary objective was to evaluate the in-hospital mortality and new permanent pacemaker (PPM) placement after SM and ASA in 3 age groups. In total, 9,564 patients underwent SM and 5,084 underwent ASA. Compared with the age group 18 to 39 years, the odds of in-hospital mortality after SM were similar in age group 40 to 64 years and 4.46 times higher than in age group ≥65 years; the higher mortality in the older group was explained by higher co-morbidity burden on the risk-adjusted analysis. Furthermore, compared with age group 18 to 39 years, the odds of new PPM placement after SM were higher in the age groups 40 to 64 years and ≥65 years, despite the risk adjustment (adjusted odds ratio [AOR] 3.17, 95% confidence interval [CI] 1.33 to 7.58 and AOR 4.39, 95% CI 1.78 to 10.8, respectively). The odds of in-hospital mortality after ASA were similar in age groups 65 to 79 years and 18 to 64 years. However, the odds of in-hospital mortality were higher in the age group ≥80 years than in the age group 18 to 64 years, although this difference were not present after risk adjustment. The odds of new PPM after ASA were higher for the age groups 65 to 79 years and ≥80 years than age group 18 to 64 years, despite the risk adjustment (AOR 1.78, 95% CI 1.22 to 2.60 and AOR 3.10, 95% CI 2.09 to 6.57, respectively). Finally, we also estimated these absolute risks in different age groups. In conclusion, this national data will inform health care providers to better understand the aged-based risks of outcomes after septal reduction therapy.