The effect of different exercise modalities on the maximal left ventricular outflow tract gradient in patients with obstructive hypertrophic cardiomyopathy

Background Assessment of maximally provoked LVOT obstruction (LVOTO) guides treatment decisions in obstructive hypertrophic cardiomyopathy (HCM). Guidelines recommend various maneuvers, with exercise stress echocardiography (ESE) as the preferred method if others fail. Comparative data are limited. Therefore, in this prospective study, 20 patients with obstructive HCM underwent transthoracic echocardiography (TTE) with continuous wave Doppler measuring LVOT gradients at rest, during the Valsalva maneuver, handgrip exercise at 30% and 50% of maximal hand force, squats, and bicycle ESE, with the aim of comparing commonly used maneuvers and evaluating handgrip exercise as a potential alternative for eliciting LVOTO. Results The mean resting LVOT gradient was 38.9 ± 31.4 mmHg. Handgrip exercise caused no significant change of LVOT gradients. In contrast, gradients increased markedly during the Valsalva maneuver (98.9 ± 52.8 mmHg), squats (120.3 ± 68.8 mmHg), and bicycle ESE (83.4 ± 43.3 mmHg; p < 0.001 vs. rest). There was no significant difference between Valsalva, squats, and ESE ( p = NS). Squats induced the maximal gradient in 50% of patients. Performance time was significantly shorter for the Valsalva maneuver (15 s) and squats (1 min 23 s ± 28 s) than for bicycle ESE (15 min 54 s ± 5 min 46 s; p < 0.01). Conclusion The Valsalva maneuver, squats, and bicycle ESE are equally effective in provoking LVOTO, whereas handgrip exercise is not. Given their simplicity, low cost, and shorter testing time, squats may serve as a practical adjunct to the Valsalva maneuver for LVOT gradient provocation in routine clinical assessment of obstructive HCM. Clinical trial registration German Clinical Trials Register (ID: DRKS00034473).