Dynamic left ventricular outflow tract obstruction evoked by exercise echocardiography: prevalence and predictive factors in a prospective study

Aims: In patients without hypertrophic obstructive cardiomyopathy (HOCM), dynamic left ventricular outflow tract obstruction (DLVOTO) can cause ischaemia. Little is known about incidence and predictors of DLVOTO in patients without HOCM. Methods and results: In 300 patients referred for exercise echocardiography, assessment of DLVOTO at rest and with Valsalva and of the presence of systolic anterior motion of the mitral valve leaflets (SAM) was performed. Within 90 s post-exercise, wall motion, SAM, and DLVOTO were assessed again. A significant DLVOTO was defined as late-peaking Doppler velocity of ≥2.5 m/s (25 mmHg). Excluded were 7 patients with HOCM and 13 with inadequate image quality. There were 280 patients, aged 64(11) years. Coronary artery disease was found in 38% of patients; 44% were receiving beta-blocker therapy and 35% had hypertension. At rest, ejection fraction was 59 ± 9%; left ventricular hypertrophy (LVH) was present in 21%, SAM in 16%, DLVOTO ≥25 mmHg at rest in 0.7%, and with Valsalva in 3%. At peak, echocardiographic signs of ischaemia occurred in 44%, and significant DLVOTO in 5% (13 patients). By multivariate analysis, it was found that independent predictors of significant DLVOTO at peak were chordal SAM at peak, smaller left ventricle at end-systole, higher systolic blood pressure at peak, younger age and increased septal wall thickness. Significant DLVOTO was a possible cause of symptoms and/or ischaemia in at least 6 of the 13 patients. Conclusion: Haemodynamically significant exercise-induced DLVOTO can occur without HOCM. Chordal SAM at peak, small, hyperdynamic left ventricles, increased septal wall thickness, and younger age are the best predictors. Keywords: Dynamic left ventricular outflow tract obstruction; Stress echocardiography; Prevalence; Exercise echocardiography; Ischaemi