Precision myectomy: Real-time on-pump intracardiac echocardiography for resection in patients with thin septa

During septal myectomy, once the heart is arrested and drained of blood on cardiopulmonary bypass, transesophageal echocardiography can no longer assess septal thickness. In the present study, we evaluated the effectiveness of on-pump intracardiac echocardiography (OPIE) for real-time intraoperative septal thickness assessment in patients with preoperative thickness ≤2.0 cm. Our hypothesis was that OPIE measurements would be conconcordant with the pre- and postcardiopulmonary bypass transesophageal echocardiography measurements that are at present the primary operative guides.

We retrospectively reviewed patients with hypertrophic cardiomyopathy and septal thickness ≤2.0 cm on transthoracic echocardiography who underwent septal myectomy from July 2017 to July 2024. The OPIE probe was introduced into the left-ventricular chamber during cardioplegic arrest, with repeated measurements to assess the depth and adequacy of resection. Septal thickness was evaluated pre-myectomy using transthoracic echocardiography, cardiac magnetic resonance imaging, transesophageal echocardiography, and OPIE. Lin's concordance correlation coefficients and Bland-Altman analyses were used to evaluate agreement between modalities.

A total of 220 patients were included with preoperative thickness ≤2.0, 56 of whom underwent myectomy with OPIE guidance. Preresection transesophageal echocardiography and OPIE demonstrated the strongest agreement of all the imaging modalities (Lin's concordance correlation coefficient, 0.81; 95% CI, 0.72-0.88), with minimal bias (-0.73) and the narrowest limits of agreement (-3.76, +2.31]. OPIE-derived resection thickness estimates were tightly clustered. In the OPIE cohort, there was 1 ventricular septal defect (1.8%) and no 30-day mortality.

OPIE is a reliable tool for intraoperative assessment of septal thickness, particularly in patients with mild hypertrophy.