Peak Gradients and Left Ventricular Outflow Tract Area in Hypertrophic Obstructive Cardiomyopathy:A 3-Dimensional Echocardiography Study.

OBJECTIVES

To evaluate the relationship between intraoperative 3-dimensional (3D) planimetry-determined left ventricular outflow tract (LVOT) area and Doppler-derived peak gradients in patients with hypertrophic obstructive cardiomyopathy (HOCM) undergoing septal myectomy and to determine whether 3D echocardiography can better differentiate true systolic anterior motion-related anatomic obstruction from other causes of elevated gradients.

DESIGN

A retrospective, single-center, observational study.

SETTING

A single tertiary university hospital performing septal myectomy for HOCM.

PARTICIPANTS

Thirty-six patients undergoing septal myectomy for symptomatic HOCM between February 2021 and December 2024.

INTERVENTIONS: Real-time 3D echocardiography was performed during pre-bypass procedural planning. Dobutamine stress echocardiography was conducted both before and after cardiopulmonary bypass to reproduce peak gradients and assess LVOT-mitral valve interaction. Septal myectomy was performed per standard surgical protocol.

MEASUREMENTS AND MAIN

RESULTS

LVOT area was quantified using multiplanar reconstruction during stress echocardiography, and continuous-wave Doppler gradients were measured before and after myectomy. Preoperatively, stress augmentation resulted in a median 58.2% reduction in LVOT area at peak gradient levels previously associated with symptoms in the awake state. After myectomy, peak gradients decreased significantly (median, 11.5-24.0 mmHg; p < 0.001), with only a 16.9% reduction in LVOT area. A strong preoperative correlation was observed between LVOT area and peak gradient (r = -0.64, p < 0.001), which was weaker postoperatively (r = -0.30, p = 0.018). Postoperatively, 22% of patients showed elevated peak gradients without demonstrable LVOT obstruction.

CONCLUSIONS

Intraoperative 3D echocardiography enables precise, real-time quantification of LVOT obstruction in HOCM and enhances intraoperative assessment during septal myectomy. It may improve clinical decision making in patients with high intracavitary gradients by differentiating true LVOT obstruction from residual functional gradients.