Abstract Background The microaxial flow pump (mAFP) improve survival in selected patients with ST-elevation myocardial infarction-induced cardiogenic shock (STEMI-CS). Understanding the impact on cardiac output (CO) cardiac power output (CPO) and pulmonary artery pressure (PAP) is crucial for optimizing patient management and understanding the effect of the device. Purpose To determine the effect of mAFP on hemodynamics in STEMI-CS. Methods Substudy of the Danish-German (DanGer) shock trial, an international multicentre open-label randomized trial allocating patients with STEMI-CS to mAFP or standard of care. STEMI patients with systolic blood pressure 100 mmHg or ongoing use of vasopressor and lactate 2.5 mmol/L and left ventricular ejection fraction 40% were eligible. Key exclusion criteria were comatose patients resuscitated from cardiac arrest patients with right ventricular failure and patients with mechanical infarct related complication. In addition, only patients admitted to cardiac intensive care unit (CICU) with hemodynamic monitoring using a pulmonary artery catheter were enrolled. Outcome measures were CO, CPO and mean PAP in addition native CO was estimated as CO minus estimated mAFP flow. Hemodynamic outcome measures were recorded at predefined time points during first 48 hours. Results Of 355 patients randomized 324 were admitted to CICU, 223 patients (68%) had hemodynamic monitoring, 98 (62%) in control group and 125 patients in mAFP group (74%). Patients with hemodynamic monitoring had a median age of 67 years, were predominantly males with a median systolic blood pressure on randomization of 84 mmHg, a median lactate of 4.3 mmol/L, and a median ejection fraction of 25%. Groups were well balanced. Total CO measured within 3 hours of arrival to the CICU had a median value of 3.4 L/min IQR 2.6 – 4.4 in standard of care group compared to 3.7 L/min 3.2 – 4.5 in the mAFP group (p=0.13). After the initial 6 hours in the CICU CO increased in both groups, but increased by a greater amount in the mAFP group so that CO was significantly greater from hour 3 through hour 48 (Figure). mAFP flow upon arrival to the CICU was 3.1 L/min 2.8 – 3.3. Native CO was 0.8 L/min 0.0 – 1.3 and remained low for the first 6 hours and increased significantly thereafter (Figure). First measured CPO within 3 hours of arrival to the CICU was 0.56 W 0.41 – 0.76 in standard of care and 0.68 W 0.51 – 0.85 in mAFP group, p=0.01 and remained higher in mAFP patients until 48 hours. The first measured mPAP within 3 hours of arrival to the CICU had a median value of 31 mmHg 29 – 39 in the standard of care group compared to 27 mmHg 23 – 33 in the mAFP group (p0.001). mPAP subsequently dropped in both groups but was consistently lower in the mAFP group until 48 hours (Figure). Conclusion Use of a mAFP unloads the left ventricle by reducing native CO and PAP while maintaining CPO in STEMI-CS.
Moller et al. (Sat,) studied this question.