Abstract 18899: Isoproterenol Challenge Predicts Symptomatic Response to Myectomy in Hypertrophic Cardiomyopathy With Occult Obstruction
Background: Septal myectomy is the gold standard for medically-refractory patients with hypertrophic obstructive cardiomyopathy (HCM). There is a subset of patients who have severe exertional symptoms without a resting or provocable left ventricular outflow tract (LVOT) gradient on noninvasive testing. These patients may demonstrate obstruction on hemodynamic catheterization with isoproterenol challenge but is has remained unclear how they respond to septal reduction therapy. We aimed to assess the ability of isoproterenol challenge to predict symptom resolution with myectomy in a selected HCM population.
Methods: Between February 2003 and April 2009, 18 symptomatic HCM patients (NYHA class III or IV) with labile obstruction on isoproterenol challenge underwent surgical myectomy and were reassessed for symptom resolution after a median of 4 (IQR 3-7) years.
Results: Post-myectomy, 13 patients (72.2%) had complete symptom resolution, while 5 (27.8%) had improved but persistent symptoms. Patients with complete symptom resolution had a greater increase in left atrial pressure (LAP) and tau with isoproterenol [3 (IQR -2-8) mmHg vs. -5 (IQR -8.5--1) mmHg; p=0.01] and [-0.7 (IQR -13-22) ms vs. -44 (IQR -48--0.2) ms; p=0.03] (Figure 1). The mean change in LVOT gradient with peak isoproterenol was significantly greater among patients with complete symptom resolution compared to patients with improved but persistent symptoms [(104 (IQR 66-123) mmHg vs. 55 (IQR 38-74) mmHg; p=0.01). All patients with increase in LAP with isoproterenol and LVOT gradient >100 mmHg achieved complete symptom resolution.
Discussion: Patients with residual symptoms post-myectomy had less increase in LAP and tau with isoproterenol indicating a “fixed” component to diastolic filling, as opposed to patients with symptom resolution whose response was indicative of elevation in filling pressures secondary to dynamic obstruction.
Author Disclosures: M. Prasad: None. J. Geske: None. S. Ommen: None. P. Sorajja: None. H.V. Schaff: None. B. Gersh: None. R.A. Nishimura: None.
- © 2014 by American Heart Association, Inc.