Background characteristics of the patients.
Table 1 summarizes the clinical characteristics of the patients. The male patient ratios of the ECPELLA (76%) and IABP+VA-ECMO (74%) groups were higher than those of the VA-ECMO group (50%, p=0.02). The bystander-CPR rate in VA-ECMO was higher than that in the other groups (83% in ECPELLA, 85% in IABP+VA-ECMO, and 98% in VA-ECMO, p=0.03). While shockable rhythms were seen in both the ECPELLA (48%) and IABP + VA-ECMO (47%) groups, no cases were seen in the VA-ECMO group (0%, p<0.001). Pulseless electric activity in VA-ECMO was higher than that in the other groups (41% in ECPELLA, 47% in IABP + VA-ECMO, and 88% in VA-ECMO, p<0.001). Rates of out-of-hospital cardiac arrest (OHCA) were higher in ECPELLA (41%) and IABP + VA-ECMO (42%) than in VA-ECMO (19%, p=0.02). Higher rates of acute coronary syndrome were seen in ECPELLA (66%) and IABP+VA-ECMO (56%) than in VA-ECMO (24%, p = 0.0003). Both Door to ECMO time (23 min in ECPELLA, 36 min in IABP + VA-ECMO, and 39 min in VA-ECMO, p=0.005) and Collapse to ECMO time (27 min in ECPELLA, 49 min in IABP + VA-ECMO, 36 min in VA-ECMO, p=0.004) were shorter in the ECPELLA group.
Changes in hemodynamic parameters, serum lactate, and vasoactive inotrope score.
Figure 2A shows changes in MCS flows from support day 1 to day 3. The ECPELLA group had a significantly higher MCS flow than the other groups on days 1 and 2 (P<0.05). While the mean arterial pressure (Figure 2B) was similar among the treatment groups, the VA-ECMO group showed significantly higher mean main pulmonary artery pressure (mPAP, Figure 2C) and central venous pressure (CVP) on day 1 than the other groups (P<0.05, Figure 2D).
While rates of serum lactate levels greater than 4 mmol/L (Lact-4) were decreased from E-CPR to support day 3 in all groups, the VA-ECMO group was higher than the other groups at E-CPR. On support day 1, the IABP+VA-ECMO group showed the highest rates of Lact-4 among the groups. On days 2 and 3, the rates of Lact-4 in the VA-ECMO group were higher than those in the other groups, and the ECPELLA group showed the lowest Lact-4 rates among the groups (Figure 3 left panel).
The vasoactive inotrope score was calculated as dopamine dose (μg/kg/min) + dobutamine dose (μg/kg/min) + 100 × epinephrine dose (μg/kg/min) + 10 × milrinone dose (μg/kg/min) + 10000 × vasopressin dose (unit/kg/min) + 100 × norepinephrine dose (μg/kg/min). While the rate of VIS more than 10 (VIS-10) of IABP+VA-ECMO group was lower than other groups on day 1, both IABP+VA-ECMO and ECPELLA showed lower VIS-10 rates on days 2 and 3 compared to VA-ECMO group suggesting VA-ECMO group required more vasoactive inotropes from MSC support days 1 to 3 (P<0.05, Figure 3).
VA-ECMO weaning and rate of Cerebral Performance Category Score 1 or 2.
The VA-ECMO weaning rates were 62% in ECPELLA, 44% in IABP + VA-ECMO, and 17% in VA-ECMO. The VA-ECMO weaning rate in the ECPELLA group was significantly higher than that in the other groups (P=0.0002). The rates of cerebral performance category 1 or 2 in the ECPELLA, IABP + VA-ECMO, and VA-ECMO groups were 31%, 13%, and 7%, respectively, indicating that the ECPELLA group had better neurological outcomes than the other groups (P=0.02) (Table 2).
Cumulative 30-day survival rates and factors affecting survival.
The Kaplan-Meier survival analysis revealed that cumulative 30-day survival rates were 55% in ECPELLA, 23% in IABP + VA-ECMO, and 9.5% in VA-ECMO (P<0.001, Figure 4). Multivariate Cox regression analysis for 30-day survival revealed that older age (per 10-year increment, HR: 1.30, 95% confidential interval (95% CI): 1.13-1.52, p=0.005) and longer Collapse to VA-ECMO Time (per 10-minute increment, HR: 1.22, 95% CI: 1.13-1.31, p<0.0001) increased the risk of survival. Among treatment modalities, ECPELLA significantly reduced the risk of 30-day survival compared to IABP+VA-ECMO (HR: 0.46, 95% CI: 0.24-0.88, P=0.02, Table 3), whereas single VA-ECMO significantly increased the risk compared to IABP+VA-ECMO treatment (HR: 1.86, 95% CI: 1.16-2.99, P=0.01, Table 3).