Prevalence of exercise-induced left ventricular outflow tract obstruction in symptomatic patients with non-obstructive hypertrophic cardiomyopathy.
BACKGROUND
Resting left ventricular outflow tract obstruction (LVOTO) occurs in 25% of patients with hypertrophic cardiomyopathy (HCM) and is an important cause of symptoms and disease progression. The prevalence and clinical significance of exercise induced LVOTO in patients with symptomatic non-obstructive HCM is uncertain.


RESULTS
87 symptomatic patients (43.3 (13.7) years, 67.8% males) with HCM and no previously documented LVOTO (defined as a gradient >or=30 mm Hg) underwent echocardiography during upright cardiopulmonary exercise testing: 54 patients (62.1%; 95% CI 51.5 to 71.6) developed LVOTO during exercise (latent LVOTO); 33 (37.9%; 95% CI 28.4 to 48.5) had neither resting nor exercise LVOTO (non-obstructive). Patients with latent LVOTO were more likely to have systolic anterior motion of the mitral valve (SAM) at rest (relative risk 2.1, 95% CI 1.2 to 3.8; p = 0.01), and higher peak oxygen consumption (mean difference: 10.3%, 95% CI 2.1 to 18.5; p = 0.02) than patients with non-obstructive HCM. The only independent predictors of Delta gradient during exercise were a history of presyncope/syncope, incomplete/complete SAM at rest and Wigle score (all p<0.05). Subsequent invasive reduction of LVOTO in 10 patients with latent obstruction and drug refractory symptoms resulted in improved functional class and less syncope/presyncope (all p<0.05).


CONCLUSIONS
Approximately two-thirds of patients with symptomatic non-obstructive HCM have latent LVOTO. This study suggests that all patients with symptomatic non-obstructive HCM should have exercise stress echocardiography.
Shah
J S
JS
The Heart Hospital, University College London, UK.
Esteban
M T T
MT
Thaman
R
R
Sharma
R
R
Mist
B
B
Pantazis
A
A
Ward
D
D
Kohli
S K
SK
Page
S P
SP
Demetrescu
C
C
Sevdalis
E
E
Keren
A
A
Pellerin
D
D
McKenna
W J
WJ
Elliott
P M
PM
D000293:Adolescent; D000328:Adult; D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000209:etiology* / Q000503:physiopathology; D004452:Echocardiography; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D014694:Ventricular Outflow Obstruction / Q000209:etiology* / Q000503:physiopathology