ORIGINAL ARTICLES

Prevalence of exercise-induced left ventricular outflow tract obstruction in symptomatic patients with non-obstructive hypertrophic cardiomyopathy

J S Shah¹, M T T Esteban¹, R Thaman¹, R Sharma¹, B Mist¹, A Pantazis¹, D Ward¹, S K Kohli¹, S P Page¹, C Demetrescu¹, E Sevdalis¹, A Keren², D Pellerin¹, W J McKenna¹, P M Elliott¹

¹ The Heart Hospital, University College London, UK
² Hadassah University Hospital, Kirjat Hadassah Jerusalem, Israel

Dr Perry Elliott, The Heart Hospital, 16-18 Westmoreland Street, London W1G 8PH, UK; pelliott{at}doctors.org.uk

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.

Methods and results: 87 symptomatic patients (43.3 (13.7) years, 67.8% males) with HCM and no previously documented LVOTO (defined as a gradient 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 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.

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Online, 15 Feb 2008 [Full text]