Novel scoring system specific for patients treated with micro-axial percutaneous left ventricular assist device

BACKGROUND: Cardiogenic shock (CS) is characterized by high mortality. The impact of micro-axial percutaneous left ventricular assist devices (ma-pLVAD) remains unclear. Nevertheless, the utilization of these devices increased lately which binds considerable resources. Accurate prognosis assessment is crucial for physicians to identify patients who may benefit from the device upfront.

PURPOSE: We developed a novel scoring system predicting 30-day all-cause mortality specifically for CS patients treated with ma-pLVAD.

METHODS: Data were collected from an ongoing Impella registry including more than 830 patients since 2014. Among them, 460 patients received a ma-pLVAD in CS. Based on 53 clinically relevant parameters univariate logistic regressions on 30-day-mortality were performed. Subsequently, parameters with a p-value < 0.1 were included in a multivariate logistic regression analysis (MLRA) using backwards selection by likelihood ratio. The remaining continuous parameters underwent a correlation and regression tree analysis (CART) to define the optimal thresholds and MLRA was performed on all the selected parameters for calculation of odds ratios. These were used for score building. All-cause mortality was assessed by Kaplan-Meier method. Area under the curve (AUC) based on receiver operating characteristic (ROC) was estimated to determine the predictive value of the novel score for 30-day-mortality. Validation was performed on a timely independent cohort of CS patients treated with ma-pLVAD.

RESULTS: Patients were 68±1 years old with predominance of male gender (74.4% [n=342]). CS was mainly caused by acute myocardial infarction (AMI) (60% [n=276]). A cardio-pulmonary resuscitation before ma-pLVAD was performed in 49.0% [n=215]. Initial serum lactate was 8.6±0.3 mmol/l. All-cause mortality at 30 days was 65.1±2.2% (Fig. 1A). A model of 6 parameters resulted after first MLRA. CART analysis revealed optimal thresholds for age with 68 a [Gini-coefficient (G)=0.1], for initial serum lactate with 6.5 mmol/l [G=0.042], thrombocytes with 210 Gpt/l [G=0.021], and mean arterial pressure (MAP) with 70 and 90 mmHg [G1=0.027; G2=0.008]. Results of MLRA on the 6 parameters including the determined thresholds are given in Tab. 1. A 0 to 17 point risk score resulted by using the odds ratios (Tab. 1). ROC analysis indicated strong predictive capability for 30-day mortality (ROC AUC [95% CI] 0.767 [0.722-0.811]; p<0.001; Fig. 1B), with discrimination details provided in Tab. 2. In the validation cohort, the score demonstrated favorable performance (ROC AUC [95% CI] 0.793 [0.607-0.979]; p=0.016; n=24).

CONCLUSION: We developed an internally validated, clinically feasible scoring system to estimate 30-day-mortality of CS patients treated with ma-pLVAD. Further studies are mandatory for external validation.
  MLRA RISK SCORE Odds ratio [95% CI] p-value Points Age ≥68 a 2.075 [1.254-3.433] 0.004 2.0 History of AMI 3.423 [1.678-6.984] <0.001 3.5 Catecholamines before pLVAD 3.101 [1.560-6.166] 0.001 3.0 Serum lactate ≥6,5 mmol/l 2.426 [1.451-4.056] <0.001 2.5 Thrombocyte count ≤210 Gpt/ l 2.077 [1.249-3.455] 0.005 2.0 MAP <70 mmHg 3.937 [1.420-10.917] 0.008 4.0 MAP 70- <90 mmHg 1.819 [1.064-3.112] 0.029 2.0 Tab. 1
Score points 0-8.0 8.5-10.0 10.5-13.0 13.5-17.0 Predicted mortality /% 16.7 53.1 74.3 94.6 Tab. 2