Utility of Acute Vasodilator Challenge with Inhaled Nitric Oxide to Predict Pulmonary Hemodynamic Reversibility in Patients with Pulmonary Hypertension due to Left Heart Disease Referred for Heart Transplantation

Pulmonary hypertension due to left heart disease (PH-LHD) in heart transplantation (HTx) candidates is associated with increased post-transplant mortality. Although guidelines recommend acute vasodilator challenge (AVC) with nitroprusside or milrinone, the safety and utility of inhaled nitric oxide (iNO) for AVC in this setting remain unclear.We retrospectively reviewed 18 patients with PH-LHD referred for HTx who underwent AVC with iNO. While arterial oxygen saturation decreased after AVC (95.4 ± 2.6 to 94.1 ± 2.7%, P = 0.013), there were no significant changes in mean aortic pressure (74.5 ± 9.8 versus 74.0 ± 8.0 mmHg, P = 0.680), and no respiratory or circulatory adverse events occurred. Both mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) significantly decreased (mPAP: 36.1 ± 8.0 to 33.2 ± 7.5 mmHg, P = 0.007; PVR: 5.2 ± 2.9 to 2.9 ± 1.3 Wood Units [WU], P < 0.001). Nine patients subsequently underwent left ventricular assist device (LVAD) implantation. At 1 month after implantation, PVR decreased from pre-AVC levels (4.0 ± 1.6 to 2.9 ± 1.3 WU, P = 0.049). The percent change in PVR from pre-AVC to post-LVAD correlated with the percent change from pre-AVC to post-AVC (r = 0.76, P = 0.029).Our preliminary findings suggest that AVC with iNO may be a useful method for evaluating the reversibility of elevated PVR and could indicate the hemodynamic response to LVAD implantation in patients with PH-LHD.