We reported a total of 152 subjects received VA-ECMO for PCS, which was the largest group of subjects in mainland China. The weaning rate and in-hospital mortality were 56.6% and 52.0%, respectively. Multivariate logistic regression indicated concurrent initiation of IABP with VA-ECMO was an independent protective factor for in-hospital mortality. Concurrent initiation of IABP reduced the need for continuous renal replacement therapy and the rate of neurological complications, but increased thrombotic risk.
In such a critical situation as PCS, VA-ECMO is widely used to facilitate myocardial recovery. VA-ECMO supporting in PCS has favorable long-term outcomes, but a high risk of in-hospital mortality [8]. Therefore, short-term outcomes ought to be the key point in quality improvement. As there is no specific guideline for VA-ECMO use in PCS, the decision for initiation of VA-ECMO is mainly made by personal experience of the surgical team. Herein, we summarized our experience in order to improve the outcomes of VA-ECMO for PCS in the future.
The general survival rate of discharge was comparable to previous studies [9]. Different risk factors for ECMO use in PCS, such as age, diabetes, pulmonary hypertension, atrial fibrillation and CABG procedure, were identified in previous studies [10,11,12,13]. In univariate analysis, we identified hypertension, LVEDD, secondary thoracotomy before ECMO initiation, pre-ECMO cardiac arrest or ventricular fibrillation, bedside initiation of ECMO and initiation of ECMO after IABP, which represented more terrible conditions, were risk factors for in-hospital mortality, while heart transplantation, lower LVEF and concurrent IABP initiation with ECMO were identified as protective factors for in-hospital mortality. Different from previous studies, which included more CABG or valvular surgeries [9], we had more heart transplant procedures in our study. Additionally, as there were more heart transplantation procedures in survivor group, suggesting a more subjects with end-stage heart failure at baseline in survivor group, we found the mean LVEF was lower in survivor group. In order to eliminate the effect of specific surgical procedure on survival, we applied multivariate logistic regression to identify the independent factor associated with in-hospital mortality. In multivariate analysis, we found concurrent initiation of IABP with VA-ECMO was the only independent protective factor for in-hospital mortality.
It has been controversial for a long time whether additional use of IABP could improve survival or not [14,15,16,17]. As previous study included subjects for all indications, confounding factors might be induced when interpreting the yield of combined use of VA-ECMO and IABP. Moreover, previous studies on VA-ECMO in subjects with PCS did not concern about the time sequence for initiating VA-ECMO and IABP. In this study, we took the time sequence of initiation of VA-ECMO and IABP into consideration, so we found concurrent initiation of IABP with VA-ECMO could bring better outcomes. As we know, VA-ECMO increases left ventricular (LV) afterload and decreases the blood flow in coronary artery due to retrograde blood flow, which potentially deteriorates cardiac function. An IABP could reduce LV afterload and increase the blood flow of coronary artery by providing pulsatile flow through inflating during diastole and deflating during systole. Additionally, in such condition as PCS, surgical procedure refined the structural defect of the diseased heart. Reduced LV afterload and increased the blood flow of coronary artery would promote myocardial recovery Therefore, it could improve survival when initiating IABP concurrently with VA-ECMO in such subgroups of patients with PCS.
As pulsatile flow provides better peripheral perfusion, concurrent initiation of IABP with ECMO would improve the blood supply for the kidney and the brain. Therefore, it would be the mechanism for concurrent initiation could reduce the need for continuous renal replacement therapy and decrease neurological complications. However, as additional implantation of IABP increased extracorporeal circuit, which brought extra strike on coagulation system, it put the subjects under more risk of thrombosis. Thus, it would be cautious to monitor blood coagulation and thrombosis in this group of subjects.
In summary, in order to improve the short-term survival and reduce complications related to peripheral perfusion, we suggest concurrent initiation of IABP with VA-ECMO in subjects with PCS if there are no contraindications. Meanwhile, an additional attention should be paid on monitoring coagulation function and potential thrombosis complications.
Limitations
As a single-center retrospective study, this study is subject to all limitations of a non-randomized study. Our findings need to be further confirmed in a larger multicenter cohort or a randomized controlled trial.