Early and mid-term outcome of inhaled versus intravenous milrinone in patients with rheumatic mitral stenosis and pulmonary hypertension undergoing mitral valve surgery

Abstract

Objective: Inhalational milrinone (iMiL) leads to reduction in pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) in patients suffering from pulmonary arterial hypertension (PAH) with use of systemic vasodilatation compared to intravenous milrinone (IVMil). Our study was aimed to compare the effect of inhaled versus intravenous milrinone on perioperative and mid-term outcome in patients with rheumatic severe mitral stenosis (MS) with severe PAH undergoing mitral valve replacement surgery. Methods: Between September 2017 to December 2019, a prospective observational study was performed in 150 patients with severe MS and right ventricular (RV) systolic pressure >50 mm Hg. They were divided into two groups i.e., iMil and IVMil. Various outcomes along with hemodynamic and echocardiographic parameters at baseline and at 4 different time points were noted. Results: Mean age was 35.7 (8.2) years. There were 5 deaths (1 in iMil group and 4 in IVMil group p= 0.023) and all deaths were due to acute RV failure. In iMil group, there was significant improvement in RV fractional area change (T1 to T3, p<0.001) and TAPSE parameters (T1 p<0.001, T2 p=0.004, T3 p=0.02), significant reduction in PAP and PVR (T1 to T3, p<0.001, respectively); while lesser fall in systemic vascular resistance (T1 to T3, p<0.001) compared to IVMil group. Vasopressor-inotropic score was significantly higher in IVMil group (at shifting p<0.001, after 24 hrs p<0.001, after 48 hrs p=0.002, after 72 hrs p=0.002). During follow-up, patients in both the groups had excellent survival with good functional outcomes. Conclusion: Intraoperative inhalational milrinone improves RV and systemic hemodynamics better than intravenous milrinone. It is also superior to intravenous milrinone to prevent acute RV failure, which ultimately leads to significant reduction in post-operative morbidity and mortality.

Keywords

• rheumatic mitral stenosis
• pulmonary arterial hypertension
• nebulization cardiopulmonary bypass
• milrinone