Early Effect of Pulmonary Thromboendarterectomy on Right Ventricular-to-Pulmonary Artery Coupling.

Objectives: To assess intraoperative changes in the right ventricular-pulmonary artery coupling ratio, derived using right ventricular free wall strain and invasive pulmonary artery systolic pressure, following pulmonary thromboendarterectomy (PTE).

Design: Retrospective analysis.

Setting: Tertiary academic center.

Participants: Adult patients with chronic thromboembolic pulmonary hypertension.

Interventions: Pulmonary thromboendarterectomy.

Measurements and main results: Patients were categorized based on the change in the right ventricular-pulmonary artery coupling ratio between pre- and post-bypass assessments: (a) "responders"-an increase in coupling of >0.2; and (b) "non-responders"-either no significant change (≤0.2) or a decrease in coupling of >0.2. Paired t-tests were used to compare coupling, right ventricular free wall strain, and pulmonary artery systolic pressure before and after PTE. Of 67 identified patients, 11 (16%) were classified as responders, while 56 (84%) were classified as non-responders. No significant change in coupling was observed before and after PTE for the entire population (mean difference [95% CI]: 0.03 [- 0.02, 0.08], p = 0.28). The success of the PTE was confirmed by intraoperative reduction of pulmonary artery systolic pressure (mean difference [95% CI]: -15.5 [-19.8, -11.2] mmHg, p < 0.01), improvement in the 6-minute walk test (mean difference [95% CI]: 164 [76, 251] feet, p < 0.01), and a reduction in pulmonary vascular resistance (mean difference [95% CI]: -2.94 [-4.16, -1.71] WU, p < 0.01) at 6 months post-PTE.

Conclusion: In the majority of patients, despite successful PTE, early measurement of the coupling ratio may not show improvement. Immediate intraoperative hemodynamic or echocardiographic parameters lack the predictability to detect "responders" to surgical success.