title: Safety profile and utility of treadmill exercise in patients with high-gradient hypertrophic cardiomyopathy.
abstract: Exercise echocardiography in the evaluation of hypertrophic cardiomyopathy (HCM) provides valuable information for risk stratification, selection of optimal treatment, and prognostication. However, HCM patients with left ventricular outflow tract gradients ≥30mm Hg are often excluded from exercise testing because of safety considerations. We examined the safety and utility of exercise testing in patients with high-gradient HCM.
  
  
  
  We evaluated clinical characteristics, hemodynamics, and imaging variables in 499 consecutive patients with HCM who performed 959 exercise tests. Patients were divided based on peak left ventricular outflow tract gradients using a 30-mm Hg threshold into the following: obstructive (n=152), labile-obstructive (n=178), and nonobstructive (n=169) groups.
  
  
  
  There were no deaths during exercise testing. We noted 20 complications (2.1% of tests) including 3 serious ventricular arrhythmias (0.3% of tests). There was no difference in complication rate between groups. Patients with obstructive HCM had a higher frequency of abnormal blood pressure response (obstructive: 53% vs labile: obstructive: 41% and nonobstructive: 37%; P=.008). Obstructive patients also displayed a lower work capacity (obstructive: 8.4±3.4 vs labile obstructive: 10.9±4.2 and nonobstructive: 10.2±4.0, metabolic equivalent; P<.001). Exercise testing provided incremental information regarding sudden cardiac death risk in 19% of patients with high-gradient HCM, and we found a poor correlation between patient-reported functional class and work capacity.
  
  
  
  Our results suggest that exercise testing in HCM is safe, and serious adverse events are rare. Although numbers are limited, exercise testing in high-gradient HCM appears to confer no significant additional safety hazard in our selected cohort and could potentially provide valuable information.
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD; Department of Cardiology, Gentofte Hospital, Copenhagen, Denmark.
authors.forename: Lars Lindholm
authors.initials: LL
authors.lastname: Sorensen
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD; China Medical University, Taichung, Taiwan.
authors.forename: Hsin-Yueh
authors.initials: HY
authors.lastname: Liang
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD.
authors.forename: Aurelio
authors.initials: A
authors.lastname: Pinheiro
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD.
authors.forename: Alex
authors.initials: A
authors.lastname: Hilser
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD.
authors.forename: Veronica
authors.initials: V
authors.lastname: Dimaano
authors.affiliation: Department of Cardiology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Niels Thue
authors.initials: NT
authors.lastname: Olsen
authors.affiliation: Department of Cardiology, Gentofte Hospital, Copenhagen, Denmark.
authors.forename: Thomas Fritz
authors.initials: TF
authors.lastname: Hansen
authors.affiliation: Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Sogaard
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Nowbar
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD.
authors.forename: Chiara
authors.initials: C
authors.lastname: Pisanello
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD.
authors.forename: Iraklis
authors.initials: I
authors.lastname: Pozios
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD.
authors.forename: Susan
authors.initials: S
authors.lastname: Phillip
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD.
authors.forename: Xun
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD.
authors.forename: Roselle
authors.initials: R
authors.lastname: Abraham
authors.affiliation: Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, MD. Electronic address: tabraha3@jhmi.edu.
authors.forename: Theodore P
authors.initials: TP
authors.lastname: Abraham
mesh_terms: D000328:Adult; D000368:Aged; D000787:Angina Pectoris / Q000209:etiology; D001145:Arrhythmias, Cardiac / Q000209:etiology*; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004417:Dyspnea / Q000209:etiology; D025401:Echocardiography, Stress / Q000009:adverse effects*; D005080:Exercise Test / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013575:Syncope / Q000209:etiology*; D017180:Tachycardia, Ventricular / Q000209:etiology; D014693:Ventricular Fibrillation / Q000209:etiology; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging* / Q000503:physiopathology