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Abstract
Heart failure (HF), characterized by excessive exertional dyspnea, is a common complication
within the broad clinical spectrum of hypertrophic cardiomyopathy (HCM). HF has become
an increasingly prominent management issue with the reduction in sudden deaths due
to use of implantable defibrillators in this disease. Exertional dyspnea ranges in
severity from mild to severe (New York Heart Association functional classes II to
IV) and not uncommonly becomes refractory to medical management, leading to progressive
disability, but largely in the absence of pulmonary congestion and volume overload
requiring hospitalization. HCM-related HF is most commonly due to dynamic mechanical
impedance to left ventricular outflow produced by mitral valve systolic anterior motion,
leading to high intracavity pressures. Surgical septal myectomy with low operative
mortality (<1%) produces HF reversal and symptom relief in 90% to 95% of patients,
while also conveying a survival benefit. Exercise echocardiography has assumed an
important role in the evaluation of patients with HCM, i.e., by identifying candidates
for septal reduction therapy with refractory HF when outflow gradients are present
only with physiological exercise, distinguishing highly symptomatic nonobstructive
patients as heart transplant candidates, and predicting future development of progressive
HF. Notably, mortality directly attributable to HF has become exceedingly uncommon
in HCM (<0.5%/year) in contrast with HF in non-HCM diseases (by 20-fold). In conclusion,
HF in HCM is associated with diverse and complex pathophysiology, but a substantially
more favorable prognosis than conventional non-HCM HF, and highly amenable to effective
treatment options in the vast majority of patients.