Repetitive Squat-to-Stand Provocation of Dynamic Left Ventricular Outflow Tract Obstruction in Hypertrophic Cardiomyopathy

Abstract

Left ventricular outflow tract (LVOT) obstruction is a determinant in the management of patients with hypertrophic cardiomyopathy, including candidacy for septal reduction therapy and risk stratification for sudden cardiac death. 1 Elliott P.M. Gimeno J.R. Tomé M.T. Shah J. Ward D. Thaman R. et al. Left ventricular outflow tract obstruction and sudden death risk in patients with hypertrophic cardiomyopathy. Eur Heart J. 2006; 27: 1933-1941 Crossref PubMed Scopus (262) Google Scholar ,2 Ommen S.R. Mital S. Burke M.A. Day S.M. Deswal A. Elliott P. et al. 2020 AHA/ACC guideline for the diagnosis and treatment of patients with hypertrophic cardiomyopathy. J Am Coll Cardiol. 2020; 76: e159-e240 Crossref PubMed Scopus (136) Google Scholar Obstruction is defined as a maximal instantaneous gradient ≥ 30 mm Hg, and severe obstruction is defined as a maximal instantaneous gradient ≥ 50 mm Hg. 2 Ommen S.R. Mital S. Burke M.A. Day S.M. Deswal A. Elliott P. et al. 2020 AHA/ACC guideline for the diagnosis and treatment of patients with hypertrophic cardiomyopathy. J Am Coll Cardiol. 2020; 76: e159-e240 Crossref PubMed Scopus (136) Google Scholar Several provocative maneuvers have been used to elicit latent obstruction, including the Valsalva maneuver, amyl nitrite inhalation, and exercise on a treadmill or bike. 3 Marwick T.H. Nakatani S. Haluska B. Thomas J.D. Lever H.M. Provocation of latent left ventricular outflow tract gradients with amyl nitrite and exercise in hypertrophic cardiomyopathy. Am J Cardiol. 1995; 75: 805-809 Abstract Full Text PDF PubMed Scopus (74) Google Scholar , 4 Jensen M.K. Havndrup O. Pecini R. Dalsgaard M. Hassager C. Helqvist S. et al. Comparison of Valsalva manoeuvre and exercise in echocardiographic evaluation of left ventricular outflow tract obstruction in hypertrophic cardiomyopathy. Eur J Echocardiogr. 2010; 11: 763-769 Crossref PubMed Scopus (24) Google Scholar , 5 Shah J.S. Esteban M.T.T. Thaman R. Sharma R. Mist B. Pantazis A. et al. Prevalence of exercise-induced left ventricular outflow tract obstruction in symptomatic patients with non-obstructive hypertrophic cardiomyopathy. Heart. 2008; 94: 1288-1294 Crossref PubMed Scopus (165) Google Scholar During a recent shortage of amyl nitrite, our practice implemented a repetitive squat-to-stand maneuver as an adjunct to the Valsalva maneuver when assessing for LVOT obstruction. We sought to evaluate the efficacy of this repetitive squat-to-stand maneuver in eliciting LVOT obstruction compared with the Valsalva maneuver in a retrospective study.