Association of inhaled nitric oxide with VA-ECMO weaning and short-term outcomes in ECPELLA patients: a retrospective study

Abstract Background In recent years, veno-arterial extracorporeal membrane oxygenation (VA-ECMO) combined with the left ventricular assist device Impella (ECPELLA) has gained attention as a treatment strategy for cardiogenic shock. Inhaled nitric oxide (iNO) selectively reduces pulmonary vascular resistance, thereby decreasing right ventricular afterload and improving right ventricular function. These effects suggest that iNO may be particularly beneficial during VA-ECMO weaning in ECPELLA patients. Objective This single-center retrospective study aimed to evaluate the efficacy of iNO therapy in ECPELLA patients. Methods Between October 2018 and March 2024, a total of 138 patients received ECPELLA support at our institution. Since 2022, iNO therapy has been available, with its indication left to the discretion of the attending physician. The primary outcomes were 30-day all-cause mortality, VA-ECMO weaning rate, and VA-ECMO duration. The secondary outcomes included hemodynamic parameters, mechanical circulatory support flow, and P/F ratio, assessed before iNO administration and at 1, 4, 12 and 24 hours afterward in the iNO group. Results During the study period, 52 ECPELLA patients received iNO therapy. Patients were divided into two groups: the iNO group (n=52) and the non-iNO group (n=86). There were no significant differences in age, sex, comorbidities, medical history, prevalence of acute coronary syndrome, or rates of extracorporeal cardiopulmonary resuscitation between the groups. In the iNO group, P/F ratio significantly increased at 24 hours after iNO administration compared to baseline, while VA-ECMO flow significantly decreased. However, there were no significant changes over time in mean pulmonary artery pressure, mean arterial pressure, pulmonary artery pulsatility index, pulmonary vascular resistance, cardiac output, or Impella flow. The VA-ECMO weaning rate was significantly higher in the iNO group (85% vs. 49%; p 0.001). However, VA-ECMO duration was significantly longer in the iNO group (151 116–236 min vs. 98 47–155 min; p = 0.002) (Fig 1A), and this trend remained consistent even among patients successfully weaned from VA-ECMO (Fig 1B). Kaplan-Meier analysis demonstrated that the iNO group had a significantly higher survival rate than the non-iNO group (44% vs. 38%, p = 0.036 by log-rank test) (Fig2A). However, a progressive worsening of survival rate was observed in the iNO group after VA-ECMO weaning (Fig.2B). Conclusion In ECPELLA patients, the iNO group had a higher VA-ECMO weaning rate and improved 30-day survival, despite a longer VA-ECMO duration. These findings suggest that iNO was used in patients with greater weaning difficulty and may have facilitated VA-ECMO withdrawal. However, a progressive worsening of survival rate was observed in the iNO group after VA-ECMO weaning, indicating limited iNO benefits in the outcome of ECPELLA patients.