Hypertrophic Cardiomyopathy

Obstructive hypertrophic cardiomyopathy: a review of new therapies

Hypertrophic cardiomyopathy (HCM) is a phenotypically heterogeneous disease with a genetic basis and variable penetrance. The hallmarks of HCM include dynamic left ventricular outflow tract obstruction, typically caused by asymmetric septal hypertrophy. However, abnormal papillary muscle placement, abnormal mitral valve and subvalvular apparatus and apical hypertrophic forms have also been described. Typical medical treatment has been stagnant for decades, although there have been significant advances in surgical treatment of patients with obstructive HCM. Herein, we describe a new class of drugs targeting the specific pathophysiology of HCM.

Hypertrophic Cardiomyopathy in Children, Adolescents, and Young Adults Associated With Low Cardiovascular Mortality With Contemporary Management Strategies

Background—

Youthful age has been considered the time of greatest risk for patients with hypertrophic cardiomyopathy (HCM), largely because of the possibility of sudden death. The last 2 decades have witnessed more reliable identification of at-risk patients and utilization of implantable cardioverter-defibrillators for prevention of sudden death, and other contemporary treatment options. Whether such management advances have significantly altered the considerable mortality rate for young HCM patients remains unresolved.

Methods and Results—

We studied long-term outcome in 474 consecutive HCM patients between 7 and 29 years of age presenting at 2 referral institutions. Over 7.1±5.1 years of follow-up (6.0 [3.0, 10.0]), 452 patients (95%) survived, with 95% experiencing no or mild symptoms. HCM-related death occurred in 18 patients (3%; 0.54%/y): arrhythmic sudden death (n=12), progressive heart failure and heart transplant complications (n=5), or postoperatively (n=1). In contrast, aborted life-threatening events occurred in 63 other high-risk patients (13%) with implantable cardioverter-defibrillator interventions for ventricular tachyarrhythmias (n=31), resuscitated out-of-hospital cardiac arrest (n=20), or heart transplant for advanced heart failure (n=12), 1.8%/y, 3-fold higher than HCM mortality. Five- and 10-year survival (considering only HCM deaths) was high (97% and 94%, respectively), virtually identical to that reported in middle-aged adult HCM patients (98% and 94%, P =0.23).

Conclusions—

In a large hospital-based cohort of young HCM patients, representing an age group considered at greatest risk, low mortality rates can be achieved with the application of contemporary cardiovascular treatment strategies, largely because of reliable identification of high-risk patients who benefited from implantable cardioverter-defibrillators for sudden death prevention, thereby creating the opportunity for extended longevity and good quality of life.

Hypertrophic Cardiomyopathy in Adulthood Associated With Low Cardiovascular Mortality With Contemporary Management Strategies

BACKGROUND

Hypertrophic cardiomyopathy (HCM) has been prominently associated with adverse disease complications, including sudden death or heart failure death and a generally adverse prognosis, with annual mortality rates of up to 6%.

OBJECTIVES

This study determined whether recent advances in management strategy, including implantable cardioverter-defibrillators (ICDs), heart transplantation, or other therapeutic measures have significantly improved survival and the clinical course of adult HCM patients.

METHODS

We addressed long-term outcomes in 1,000 consecutive adult HCM patients presenting at 30 to 59 years of age (mean 45±8 years) over 7.2±5.2 years of follow-up.

RESULTS

Of 1,000 patients, 918 (92%) survived to 53±9.2 years of age (range 32 to 80 years) with 91% experiencing no or only mild symptoms at last evaluation. HCM-related death occurred in 40 patients (4% [0.53%/year]) at 50±10 years from the following events: progressive heart failure (n=17); arrhythmic sudden death (SD) (n=17); and embolic stroke (n=2). In contrast, 56 other high-risk patients (5.6%) survived life-threatening events, most commonly with ICD interventions for ventricular tachyarrhythmias (n=33) or heart transplantation for advanced heart failure (n=18 [0.79%/year]). SD occurred in patients who declined ICD recommendations, had evaluations before application of prophylactic ICDs to HCM, or were without conventional risk factors. The 5- and 10-year survival rates (confined to HCM deaths) were 98% and 94%, respectively, not different from the expected all-cause mortality in the general U.S. population (p=0.25). Multivariate independent predictors of adverse outcome were younger age at diagnosis, female sex, and increased left atrial dimension.

CONCLUSIONS

In a large longitudinally assessed adult HCM cohort, we have demonstrated that contemporary management strategies and treatment interventions, including ICDs for SD prevention, have significantly altered the clinical course, now resulting in a low disease-related mortality rate of 0.5%/year and an opportunity for extended longevity.