{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T10:55:11Z","timestamp":1788951311663,"version":"build-2803163510"},"reference-count":24,"publisher":"BMJ","issue":"10","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Heart"],"published-print":{"date-parts":[[2008,10]]},"abstract":"<jats:sec>\n                  <jats:title>Background:<\/jats:title>\n                  <jats:p>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.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods and results:<\/jats:title>\n                  <jats:p>87 symptomatic patients (43.3 (13.7) years, 67.8% males) with HCM and no previously documented LVOTO (defined as a gradient \u2a7e30 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\u200a=\u200a0.01), and higher peak oxygen consumption (mean difference: 10.3%, 95% CI 2.1 to 18.5; p\u200a=\u200a0.02) than patients with non-obstructive HCM. The only independent predictors of \u0394 gradient during exercise were a history of presyncope\/syncope, incomplete\/complete SAM at rest and Wigle score (all p&lt;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&lt;0.05).<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusions:<\/jats:title>\n                  <jats:p>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.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1136\/hrt.2007.126003","type":"journal-article","created":{"date-parts":[[2007,11,21]],"date-time":"2007-11-21T20:44:46Z","timestamp":1195677886000},"page":"1288-1294","source":"Crossref","is-referenced-by-count":207,"title":["Prevalence of exercise-induced left ventricular outflow tract obstruction in symptomatic patients with non-obstructive hypertrophic cardiomyopathy"],"prefix":"10.1136","volume":"94","author":[{"given":"J S","family":"Shah","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M T 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