Efficacy of Intraoperative Inhaled Nitric Oxide in Off-Pump Coronary Artery Bypass Grafting in Patients With Low Ejection Fraction.

BACKGROUND: One of the challenges with off-pump coronary artery bypass grafting (OPCAB) in patients with low left ventricular ejection fraction (LVEF) is the transient increase in right ventricular (RV) afterload during cardiac displacement. We developed the "iNO bundle," a protocol integrating pulmonary artery catheter (PAC)-guided navigation with titrated inhaled nitric oxide (iNO), to stabilize hemodynamics. METHODS AND RESULTS: This retrospective study evaluated 77 patients (LVEF <40%) undergoing isolated OPCAB at Kumamoto University Hospital between April 2015 and January 2026; 28 patients managed via the iNO bundle (February 2023-January 2026) were compared to 49 historical controls using inverse probability weighting. Hemodynamic instability was defined as a sustained decrease in mean arterial pressure (MAP) for >5 min, necessitating emergency conversion to on-pump surgery. In the iNO bundle group, mean pulmonary arterial pressure (PAP) decreased significantly (from 23.9 to 21.6 mmHg; P<0.001) and the MAP/PAP ratio improved (from 3.3 to 3.7; P=0.001). The pulmonary artery pulsatility index decreased in the iNO bundle group (from 2.0 to 1.6, P=0.003), suggesting therapeutic RV unloading. Notably, the incidence of emergency conversion to on-pump surgery was 0% in the iNO-Bundle group (vs. 4.1% for the historical controls). No iNO-related adverse events were observed. CONCLUSIONS: The PAC-guided iNO bundle provides a precision-medicine approach to hemodynamic management. By facilitating therapeutic RV unloading, this protocol is a proactive strategy to maintain hemodynamic stability during high-risk OPCAB.