Hypertrophic Cardiomyopathy in "Real-World" Community Cardiology Practice

Clinical Characteristics and Healthcare Resource Utilization among Patients with Obstructive Hypertrophic Cardiomyopathy Treated in a Range of Settings in the United States

Obstructive hypertrophic cardiomyopathy (oHCM) has been studied primarily in comprehensive centers of excellence. Broadening the understanding of patients with oHCM in the general population may improve identification and treatment in other settings. This retrospective cohort study identified adults with oHCM from a large electronic medical record database comprising data from 39 integrated delivery networks (IBM Explorys; observational period: January 2009–July 2019). Clinical characteristics, healthcare resource utilization (HCRU), and outcomes were reported. Of 8791 patients, 53.0% were female and the mean index age was 61.8 years. Cardiovascular drugs prescribed included beta-blockers (80.5%), calcium channel blockers (46.0%), and disopyramide (2.4%). Over time, heart failure, atrial fibrillation, and ventricular arrhythmias increased. Surgical procedures included septal myectomy (22.0%), alcohol septal ablation (0.6%), and heart transplantation (0.3%). Implantable cardioverter defibrillators were present in 11.2% of patients. After initial septal reduction therapy (SRT), HCRU increased and 550 patients (27.7%) required a reintervention. Of the overall group, 2.7% experienced sudden cardiac arrest by end of study. In conclusion, this cohort of patients with oHCM had guideline-recommended drug therapy and procedures. Despite this, heart failure, atrial fibrillation, and ventricular arrhythmias increased, and more than a quarter of patients undergoing SRT required reintervention. These unresolved issues emphasize the unmet need for new, effective therapies for patients with oHCM.

Characteristics of Patients With Obstructive Hypertrophic Cardiomyopathy in Real-World Community-Based Cardiovascular Practices

The clinical profile of patients with obstructive hypertrophic cardiomyopathy (oHC) is not well characterized, with little evidence outside selected referral populations. Using longitudinal medical claims data from a United States nationwide database, we retrospectively identified adults who were newly diagnosed with oHC. Clinical characteristics were compared from 1 year before diagnosis and at the 2-year follow-up. Patients (N = 1,841) with oHC (age 63 ± 15 years; 52% were male) with geographic representation across the United States were identified. Most patients received care within community-based cardiovascular practices and 7% at referral hypertrophic cardiomyopathy (HC) centers. Baseline diagnostic procedures included electrocardiogram (66%), echocardiogram (51%), magnetic resonance imaging (4%), and HC genetic testing (0.7%). Baseline co-morbidities were hypertension (59%), coronary artery disease (30%), diabetes (19%), and atrial fibrillation (19%). For all HC-related medications, use significantly increased after diagnosis. During follow-up, 144 patients (8%) received an implantable cardioverter-defibrillator for sudden death prevention, 99 underwent septal myectomy (5%), and 24 underwent alcohol septal ablation (1%). By the 1-year follow-up, 2% of patients had sudden cardiac arrest and 26% had atrial fibrillation, and heart failure increased from 16% to 27%. In conclusion, in a community-based population of patients with oHC, patients' age at diagnosis of oHC was older than reported for referral populations and patients had a significant co-morbidity burden. Cardiovascular medication use was appropriate, but the rate of guideline-supported surgical procedures was low.

Low Risk of Hypertrophic Cardiomyopathy With Contemporary Management Strategies Implemented in Non-Referral Regional Community-Based Practices

Major advances in diagnosis and treatment have emerged for hypertrophic cardiomyopathy (HCM), largely in major tertiary referral centers dedicated to this disease. Whether these therapeutic benefits are confined to patients in such highly selected cohorts, or can be implemented effectively in independent regional or community-based populations is not generally appreciated. We assessed management and clinical outcomes in a non-referral HCM center (n = 214 patients) in Eastern Pennsylvania. Over a 6.0 ± 3.2-year follow-up, the HCM-related mortality rate was 0.1% per year attributed to a single disease-related death, in a 49-year-old man with end-stage heart failure, ineligible for heart transplant. Fifteen patients (7%) with prophylactically placed implantable cardioverter-defibrillators (ICDs) experienced appropriate therapy terminating life-threatening ventricular tachyarrhythmias. In 23 other patients (11%; 5%/year), heart failure due to left ventricular outflow obstruction was reversed by surgical septal myectomy (n = 20) or percutaneous alcohol septal ablation (n = 3). This regional HCM cohort was similar to a comparison tertiary center referral population in terms of HCM-mortality: 0.1%/year vs 0.3%/year (p = 0.3) and ICD therapy (31% vs 16% of primary prevention implants), although more frequently with uncomplicated benign clinical course (62% vs 46%; p <0.01). In conclusion, effective contemporary HCM management strategies and outcomes in referral-based HCM centers can be successfully replicated in regional and/or non-referral settings. Therefore, HCM is now a highly treatable disease compatible with normal longevity when assessed in a variety of clinical venues not limited to tertiary centers.

Prognostic Significance of the Mitral L-Wave in Patients With Hypertrophic Cardiomyopathy

A mitral L-wave indicates advanced diastolic dysfunction with elevated left ventricular filling pressure. Previous studies have reported that the presence of a mitral L-wave is associated with a poor prognosis in patients with heart failure. However, whether the L-wave can predict adverse events in patients with hypertrophic cardiomyopathy (HC) is still unclear. Therefore, we aimed to investigate the prevalence of a mitral L-wave in patients with HC, and the prognosis of patients with or without an L-wave. We analyzed 445 patients with HC. The end points of this study were HC-related death, such as sudden death or potentially lethal arrhythmic events, heart failure-related death, and stroke-related death. A mitral L-wave was defined as a distinct mid-diastolic flow velocity after the E wave with a peak velocity >20 cm/s. The prevalence of an L-wave was 32.4% in patients with HC. Patients with an L-wave were significantly younger, more likely to be women, had higher New York Heart Association functional class, and had a higher prevalence of atrial fibrillation than did patients without an L-wave. Patients with an L-wave had a significantly higher incidence of HC-related death compared with those without an L-wave (log-rank, p < 0.001). The L-wave was an independent determinant of HC-related death in multivariate analysis adjusted for imbalanced baseline variables (adjusted hazard ratio 2.38; 95% confidence interval 1.42 to 4.01; p = 0.001). In conclusion, the presence of a mitral L-wave may be associated with adverse outcome in patients with HC.