Comparison of milrinone versus dobutamine on invasive haemodynamics in patients with advanced heart failure on home inotropes
Authors: Dagan M , Lankaputhra M , Yeung T , Warner V , Easton K , Linton A , Downes R , Vizi D , Leet A , Hare J , Taylor A , Bergin P , Patel H , Kaye D 
Published: November 2023

Abstract

Background
Home inotropic support is an established bridge to cardiac transplantation in patients with advanced heart failure. Milrinone, a phosphodiesterase 3 inhibitor, preferentially vasodilates pulmonary vasculature, thus is often chosen over dobutamine in patients with concomitant pulmonary hypertension. However, there is a paucity of data on the haemodynamic effects of milrinone in the pre-cardiac transplant population.

Purpose
We sought to examine the haemodynamic effects of milrinone vs. dobutamine out to 3 months in patients with advanced heart failure awaiting cardiac transplantation.

Methods
Patients in the home inotrope program at a quaternary referral centre from January 2000 to May 2022 were included. Retrospective analysis of echocardiographic and invasive haemodynamic studies via right heart catheterisation were performed at baseline (prior to commencement of inotrope), at 30 days (30D) and 3 months (3m).

Results
From a total of 119 patients, 57 were on milrinone and 62 on dobutamine. Non-ischaemic cardiomyopathies of various aetiologies accounted for 67%, while ischaemic cardiomyopathies accounted for 33%. Majority of patients were male (79%) with a mean age of 52±13 years. There was a significant increase in LVEF from 21±7% at baseline to 27±14% at 3m in those on dobutamine, p = 0.02. Similar increase in LVEF from 22±8% to 26±13% in the milrinone group did not reach significance, p = 0.43. Comparably, CI increased from 2.0±0.6L/min/m2 at baseline to 2.5±0.9L/min/m2 at 3m in the dobutamine cohort, p = 0.05, and from 2.0±0.7L/min/m2 at baseline to 2.3±0.6L/min/m2 at 3m in the milrinone cohort, p = 0.27. In the dobutamine cohort LVEDD was static from 68±14mm at baseline to 66±21mm at 3m, p = 0.78. LVEDD reduced from 67±11mm to 60± 9mm at 3m in the milrinone group, p = 0.09. Classification of mild right ventricular dysfunction increased from 7% to 18% after 30 days on milrinone, p= 0.2, compared to an increase from 10% to 16% in the dobutamine group, p = 0.47. Mean pulmonary artery pressure (mPAP) reduced from 34±11mmHg to 29±11mmHg at 3m in the milrinone group, p = 0.15. mPAP was static in the dobutamine group from 34±9mmHg at baseline to 34±10mmHg at 3m, p = 0.96. TPG in the milrinone group was 11.9±6.0mmHg to 12.9±6.3mmHg at 30D, with reduction at 3m to 9.6±6.3mmHg, p = 0.26. In the dobutamine group TPG remained static from 10.9±5.7mmHg at baseline to 11.4±5.1mmHg at 30D and 10.9±5.2 at 3m, p = 0.97. Wedge pressure (PCWP) reduced from 22±7mmHg at baseline to 21±7mmHg at 30D to 18±8mmHg at 3m in the milrinone group, p = 0.11. PCWP in the dobutamine group was static at 23±8mmHg at baseline to 24±5mmHg at 30D and 23±6mmHg at 3m, p = 0.92.

Conclusion(s)
Dobutamine demonstrated a significant increase in LVEF and CI out to 3 months, however milrinone demonstrated a larger improvement in RV function and greater reduction in cardiac and pulmonary pressures as compared to dobutamine. Larger studies are required to confirm these trends.Figure 1