Aims Several methods are used to induce latent left ventricular outflow tract (LVOT) gradients in patients with hypertrophic cardiomyopathy (HCM). We compared LVOT gradients induced by Valsalva manoeuvre (VM) and exercise echocardiography (EE) in patients with HCM treated with percutaneous transluminal septal myocardial ablation (PTSMA). Methods and results Left ventricular outflow tract gradients were measured at rest, during VM, and during EE in 57 patients 3.8 ± 2.8 years after PTSMA. Measurement succeeded in all patients during VM and in 96 during EE. There were no differences in LVOT gradients between VM [17 (9-33) mmHg] and EE [18 (10-30) mmHg, P = 0.31] [median (inter-quartile range)], but the differences ranged from -45 to 84 mmHg in individual patients. In 93 of patients, EE had no influence on the categorization into manifest-, latent- or non-obstructive phenotypes. The 7, who revealed LVOT gradients ≥30 mmHg only during EE, did not reach LVOT gradients of 50 mmHg. Patients improving two New York Heart Association (NYHA) classes after PTSMA had higher baseline LVOT gradients during VM [115 (72-160) vs. 88 (54-114) mmHg, P = 0.04] and a larger reduction in VM-induced LVOT gradients [80 (48-139) vs. 61 (28-83) mmHg, P = 0.02] than patients improving one NYHA class. Conclusion Valsalva manoeuvre and EE induce similar degrees of LVOT gradient, but categorization into obstructive phenotypes was not influenced by EE in more than 90 of patients. Valsalva manoeuvre should be the primary choice of stress modality in HCM patients treated with PTSMA, but EE is essential for the clinical management of the entire cohort.